NCASMDT final file

ADVANCES IN SEMICONDUCTOR MATERIALS
AND DEVICE TECHNOLOGIES

Proceedings of the National Conference, NCASMDT 2018
February 12-13, 2018
Bengaluru, India

Edited By

Dr. Dinesh K. Sharma

Dept.of Physics, School of Sciences
Jain (Deemed-to-be University)
Bengaluru 1- 560 027



ADVANCES IN SEMICONDUCTOR MATERIALS
AND DEVICE TECHNOLOGIES

Proceedings of the National Conference, NCASMDT 2018
February 12-13, 2018

Edited By

Dr. Dinesh K. Sharma

Dept. of Physics, School of Sciences
Jain (Deemed-to-be University)
Bengaluru - 560 027

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Advances in Semiconductor Materials and Device Technologies

Editorial Advisory Committee Dr. N. Sundararajan
Vice Chancellor, Jain (Deemed-to-be University), Bengaluru

Dr. Sandeep Shastri
Pro Vice Chancellor, Jain (Deemed-to-be University), Bengaluru

Late Dr. Jayagopal Uchil
Dean of Sciences, Director, Academics & Planning
Jain (Deemed-to-be University), Bengaluru

Dr. N.V.H. Krishnan
Registrar, Jain (Deemed-to-be University), Bengaluru

Dr. Varalakshmi K.N, Director-School of Sciences,
Jain (Deemed-to-be University), Bengaluru

Dr. Jamil Akhtar, CREE Pilani, Rajasthan

H.S. Jatana, SCL, Chandigarh

Dr. Ravi Kumar, Texas Instrumentation, Bengaluru

Saravanan Sethuraman, IBM, Bengaluru

Dr. Dinesh K. Sharma, Dept. of Physics, School of Sciences
Jain (Deemed-to-be University), Bengaluru

Editorial Board Dr. S. Rajagopal, Dept. of Physics, School of Sciences
Jain (Deemed-to-be University), Bengaluru

Dr. Sheela K. Ramasesha, I.I.Sc., Bengaluru

Dr. Ramakrishna Damle, Dept. of Physics
Bangalore University, Bengaluru

Dr. Sharath Ananthamurthy, Dept. of Physics
University of Hyderabad, Telangana

Dr. M.K. Kokila, Dept. of Physics
Bangalore University, Bengaluru

Dr. K.T Vasudevan, Dept. of Physics
Vijaya College, R V Road, Bengaluru

Dr. V.P. Mahadevan Pillai, Dept. of Physics
Central University of Kerala, Kerala

Dr. Mythili P. Rao, Dean-Languages
Jain (Deemed-to-be University), Bengaluru

Dr. Dinesh K. Sharma, Dept. of Physics, School of Sciences
Jain (Deemed-to-be University), Bengaluru

 5

Invited talks

Prof. S. Mohan
Emeritus Professor
Centre for Nano Science & Engineering(CeNSE)
Indian Institute of Science, Bengaluru
Theme: High K dielectric films for applications
in Nano electronic devices

Prof. Navkanta Bhat
Chairperson
Centre for Nano Science & Engineering(CeNSE)
Indian Institute of Science, Bengaluru
Theme: Nanotransistors with 2D materials

Dr. Dinesh K. Sharma
Assistant Professor
Dept. of Physics, School of Sciences
Jain (Deemed-to-be University), Bengaluru
Theme: Role of trench gate technology in semiconductor
power devices

Dr. C.P. Ravikumar
Director
Technical Talent Development
Texas Instrumentation, Bengaluru
Theme: Analog Design and Test: Challenges and Opportunities

Prof. K.N. Bhat
Emeritus Professor
Centre for Nano Science & Engineering(CeNSE)
Indian Institute of Science, Bengaluru
Theme: Hetero-junction Devices for High Speed and High
Power Applications

Prof. K.S. Narayan
Professor and Dean (R&D)
JNCASR, Jakkur, Bengaluru
Theme: Device Physics of Hybrid Perovskite Structures

Dr. Sheela Ramasesha
Principal Scientist
School of Natural Sciences and Engineering
National Institute of Advanced Studies
Indian Institute of Science Campus, Bengaluru
Theme: Nanostructured solar cell

Saravanan Sethuraman
Senior Research And Development Engineer
IBM, Bengaluru
Theme: Emerging Memory Technologies

CONTENTS

1. Editorial I
Dr. Dinesh K. Sharma II
1-4
2. Acknowledgement 5-7
8-10
3. Hetero-Junction Devices for High Speed and High Power Applications 11-14
K.N. Bhat, Emeritus Professor 15-20

4. Nanopillar Array of Cds/Cdte Thin Film Photovoltaic for Enhanced Junction Area 21-24
Murugaiya Sridar Ilango, Sheela K. Ramasesha and Dinesh Kumar 25-30
31-33
5. Effect of Substrate Temperature on the Quality of Insb Thin Films
A.G. Kunjomana and Bibin John 34-36

6. Optical and Microstructural Studies on COSO4.7H20 Filled Epoxy 37-39
Shruti S. Devangamath and Blaise Lobo
40-43
7. Design of Mems Accelerometers for Wide Band Structural Dynamic Studies
44-49
Nitish Kumar C*, M.S. Giridhar, Ashwini Jambhalikar, Gogulapati Supriya, 50-53

Bhuvan M.B. Pratheek T.K. JJohn**, R. Islam and M. Viswanathan 54-57

8. Study of the Effect of Electron Irradiation on Mosfet for Space Applications
Sujatha R , Abdul Rehman Khan, M. Ravindra and R. Damle

9. Synthesis and Characterization of Graphene Derivatives
Aparna V. Nair and Manoj B

10. Structural, Morphological and Thermal Properties of ZNS:MN
Doped Polyaniline Nanocomposites
Jayasudha Sriram1, Ramya P, Dr. Priya L,*, Dr. K.T. Vasudevan

11. Nanocrystalline Catio ceramic Powder preparation Using
Mechanochemical Method Followed by Successive Heat Treatments
Almaw Ayele Aniley, Naveen Kumar S.K and Akshaya Kumar A

12. Structural and Optical Properties of Zinc Oxide Nanoflowers
Synthesized Using Sol-Gel Method
Akshaya Kumar, S.K. Naveen Kumar and Almaw Ayele Aniley

13. Influence Radiation on Tellurium Oxide Varied Samarium Doped
Lanthanum- Lead- Borate Glasses
Madhu.A and B. Eraiah

14. Optical Studies on Zinc-Boro-Vanadate Glasses Containing Sulphate Ions
N. Sivasankara Reddy, M. Sudhakara Reddy, Asha Rajiv and C. Narayana Reddy

15. Structural, Thermal and Spectroscopic Properties of Zirconium
Oxide Incorporated Sodium Borate Glass
Roopa , B. Eraiah and A. Madhu

16. Optical and Physical Properties of Sodium Calcium Leadfluoro Borate
Glasses Incorporated With Praseodymium Ion
Susheela K. Lenkennavar, Madhu. A, B. Eraiah and M.K. Kokila

EDITORIAL

Advances in Semiconductor Materials
and Device Technologies

With ever growing complex challenges, there has been a huge development in the area of semiconductor
material, device and technology over the past half a century. Amidst this development, if anything has
remained unobjectionably unchanged in providing a predictable framework for semiconductor development
and fundamental insight into the most transformative technology thus far, has been Moore’s Law. Not only,
it has offered well defined ideas for the researchers but also endowed researcher an opportunity to focus their
research and planning for the future. However, there are signs indicating the end of the road for Moore’s law.
Where, there has been a continuous demand for area efficient, smaller and faster semiconductor devices on
the one hand, there seems to be an end of the practical path for the continually miniaturize chip designs on the
other hand.
It has been uniformly accepted that research and development must incorporate new semiconductor materials,
entirely different methods, and circuitry designs to scale-up performance and functionality further. As a result,
there is huge impetus on all partners in semiconductor supply chain to seek materials with reduced defects,
quick delivery of the product to the market, improved yield and reduced cost. Thus, the challenge in front of
the new materials is, how to ease-of the process constraints of existing technologies reaching their process
boundaries, their robustness and implementing robust systems to ensure product quality. It is an exciting time
not only for the semiconductor material industry but also for the dedicated research centres especially for new
technologies.
Jain (Deemed-to-be University) in this regard has been striving relentlessly to set up very well equipped,
dedicated research centres. In an effort to provide the requisite skills and training in par with the current
demand in research, a plethora of need based programmes have been initiated for the UG and PG students.
Consistent and relentless efforts have been used by the passionate researchers of the university to meet the
world class research standard. Research collaborations have been set up in this regard not only within India but
abroad also with premier institutes, labs, companies.

Editor

Dr. Dinesh K. Sharma
Dept. of Physics, School of Sciences, Jain (Deemed-to-be University), Bengaluru

 I

Acknowledgement

I have much pleasure in thanking Dr. Chenraj Roychand, President, Jain (Deemed-to-be University) Trust,
Bengaluru for their financial support and the very efficient help from time to time during the conference. I
would like to express my very special thanks to the Dr. N. Sundararajan, Vice Chancellor, Jain (Deemed-to-be
University), Dr. Sandeep Shastri, Pro Vice Chancellor, Jain (Deemed-to-be University), Dr. NVH Krishnan,
Registrar, Jain (Deemed-to-be University), Bengaluru, Dr. Mythili P. Rao, Dean-Languages, Jain (Deemed-to-
be University), and Dr. K. N. Varalakshmi, Director, School of Sciences, Jain (Deemed-to-be University) for
their help with the conference from the very beginning till the very end.
I would also like to place on record my deep sense of appreciation to Late Prof. Jayagopal Uchil, Dean of
Sciences, Director, Academics & Planning, Jain (Deemed-to-be University) at that time, for his timely advise,
guidance and motivation towards the conductance of the conference.
My very special thanks goes to Dr M.U.Sharma CEO Semiconductor Technology and Applied Research Centre
(A unit of SITAR - Govt. of INDIA), Bengaluru who so graciously accepted my invitation for being a chief
guest in the opening ceremony of the conference.
I would like to express my utmost gratitude to all the members of the organizing committee, the technical
program committee, and the advisory committee, who with tireless efforts and selfless dedication have made
this conference possible.
I am pleased to acknowledge the support of my sponsors Prolyx Microelectronics Pvt. Ltd and Nano chip
Solution Bengaluru. Their support and participation have created a very strong industrial relevance.
Last but not least, I would like to express my cordial thanks to each and every one of you as a presenter, an
attendee, an exhibitor, a volunteer, or any combined role of the above for your contribution and participation.

 II

HETERO-JUNCTION DEVICES FOR
HIGH SPEED AND HIGH POWER APPLICATIONS

K. N. Bhat, Emeritus Professor
Centre for Nano Science and Engineering, Indian Institute of Science, Bengaluru -560012

Abstract doped (intrinsic) region to achieve the High Electron
Mobility Transistors (HEMT) to achieve High
In this paper the impact of using hetero-junctions Electron concentration and high electron mobility. In
for achieving High Electron Mobility Transistors this paper we present thedevice structure, operation
(HEMT) for high-speed applications is first briefly principles and the performance of the AlGaAs/GaAs
presented, focusing on AlGaAs/ GaAs hetero- and AlGaN/GaN based High Electron mobility
junction device. This is followed by a detailed Transistors (HEMT) [3,4].
presentation on the AlGaN/GaN hetero-junction
device grown on on <111> Si which are normally 2. Choice of materials for High speed and
ON devices. High Voltage

Keywords: III-V Heterojunction Bipolar Transistors, Even though silicon has dominated the VLSI
algaas/gaas, High Electron Mobility Transistors, ALGAN/ technology, the materials such as GaAs and GaN have
GAN Heterojunction emerged as winners because of their ability to realize
wide band gap hetero-junction devices using AlGAs/
1. Introduction GaAs and AlGaN/GaN based devices, which can
be used for high speed and high power applications,
High Speed devices and High Power devices share because of their higher band gap combined with the
some common features and requirements [1, 2]. Both high electron mobility, as can be seen from Table-1
are n-channel devices because of the higher velocity which is readily available in the literature. It may be
of electrons compared to holes. In addition, the noted from this Table that the electron mobility and
electron density in the channel needs to be high for the energy band gap of GaAs and GaN are higher than
higher currents. These two are conflicting because those in Silicon, thus making them suitable for High
the high carrier concentration and higher doping speed as well as for high frequency devices [5]. In
density, which in turn degrades the mobility. This view of thee benefits these two materials are invariably
issueis sorted outin the hetero-junction devices, chosen for high speed hi power devices. Therefore we
where the channel of electrons is formed in the un- fist consider these two materials for the HEMT.

Table-1 Comparison of Properties of Si, GaAs, SiC and GaN

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Advances in Semiconductor Materials and Device Technologies

3. High Electron Mobility Transistors band-gap donates the electrons to the un-doped
(Hemt) substrate having a lower energy band-gap. In a
hetero-junction, these donated electrons, which
In this section the hetero-junction device structures get confined into a thin region just on the top
considering AlGaAs/GaAs and AlGaN/GaN hetero- layer of the substrate, constitute the channel
junction devices, which are referred to as the HEMT region for current flow between source and
(High Electron Mobility Transistors) have been drain of the High Electron Mobility Transistor
discussed. (HEMT). By placing N+Ohmic contacts on
the two ends of this channel, and by applying
a) AlGaAs /GaAs hetero-junction HEMT a voltage between them, the current flow is
achieved. By applying appropriate polarity
A schematic cross section of AlGaAs/GaAs voltage to the gate electrode on the wide band
hetero-junction is shown in Fig.1 and the gap top layer, the electron concentration in the
energy band diagram of this structure across channel can be controlled
the AlGaAs/GaAs layers is shown in Fig.2.
The n- type doped top layer having higher

Fig. 1. Schematic Cross section of AlGaAs/GaAs HEMT

Fig. 2. Energy band structure of AlGaAs/GaAs hetero-junction showing the notch
where the 2D gas of electrons reside

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Advances in Semiconductor Materials and Device Technologies

As these electrons move in the un-doped GaAs is even lower than that of silicon. Therefore,

substrate their mobility is high and the ionized AlGaAs/ GaAs devices are not suitable for

impurity scattering of electrons is absent. This High Voltage high power applications. In

allows the devices to function even at very low addition, it may also be noted from Table-1

temperatures down to that of liquid nitrogen. that the Critical E-field for GaN is very high

At low temperature one can achieve very and is equal to 3.5MV and that the thermal

high electron mobility. Because when ND = 0 conductivity of GaN is 1.5 W/m/K, which is
Ionized impurity scattering practically absent, three times higher than that of GaAs. Therefore

and the lattice scattering mobility μL is very in the recent years AlGaN/GaN HEMT devices

high in GaAs. The Scattering is purely due have received considerable attention for use in

to Lattice scattering. μL is very high at lower the Power Electronics area particularly because

temperatures. Therefore,in the AlGaAs./GaAs the mobility of electrons in GaN is slightly

HEMT device, the electron mobility at low better than silicon.

temperatures is high [6]. Thus b) AlGaN /GaN hetero-junction HEMT

In spite of its merits of high band-gap and
reasonably high electron mobility of 1500 cm2/
For GaAs, μ>2,50,000 cm2/Vsec V-Sec for application in power devices, the cost
at a temperature of 77K, and of bulk GaN wafer iprohibitively high to serve
is very high at 4K and it is n as substrate. Therefore, the GaN layer needs
μ>20,00,000 cm2/Vsec at 4K. In to be grown on a substrate, which is not very
view of the above, for all high speed expensive, and at the same time there should
applications AlGaAs/n be reasonably good lattice match between the
substrate and the GaN. A comparison of three
GaAs FETs have captured the marked. materials suitable for this purpose is given
However, an examination of Table.1 shows that below, on the choice of substrate for growing
the critical electric maximum field for GaAs the GaN transistor layer.
is very low and is equal to 0.4MV/cm, which

SiC Table: 2 Silicon

• Good lattice match Sapphire • (111) silicon lattice
with GaN and excel • Cheaper but thermal match with GaN is
lent thermal Conduc tolerable.
tivity. conductivity is poor
0.3W/cm/K. • Cheaper and avail
• Available in 4 inch able in large
from CREE. diameters.

• Very expensive. • Thermal conductivity,
Hundred times cost K=1.5W/cm /K.
lier than GaAs.. (Better if not the best)

Based on the above considerations the AlGaN /GaN device layer is generally carried out by the experts in
device layer is mostly grown on <111> Silicon and the MOCVD growth process . As the AlN is basically
is shown in Fig.3. It may be noted that the GaN piezoelectric and also due to the stress on the layer,
device layer is not grown directly on silicon because there is spontaneous 2D electron layer in the transition
of the lattice mismatch. Therefore a transition layer layer between the AlGaN and GaN Layer as shown
consisting of AlN and gradual transition to GaN in Fig 3. As a result this called as a Normally ON

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Advances in Semiconductor Materials and Device Technologies

device because, even at VG=0, the channel is ON. In configurations usually use a positive voltage to
order to turn off the device, a negative voltage must turn on a switch. This device can be converted into
be applied to the gate. This device can be converted a normally off device by etching up to a certain
into a normally off device by etching few layers of the depth of the top AlGaN layer. Alternately a circuit
top AlGaN layer as shown in Fig4 below. configuration called the cascade connection is used to
turn off the circuitusing a positive input voltage. Both
In order to turn off the device, a negative voltage approaches will be presented during the talk.
must be applied to the gate. However, the circuit

Fig. 3. AlGaN /GaN HEMT grown on <111> Silicon substrate

4. Summary and Conclusion 2. Millan, Jose, et al. “A survey of wide bandgap power
semiconductor devices.” IEEE transactions on Power
In this paper, Hetero-junction devices using AlGaAs/ Electronics 29.5 (2014): 2155-2163.
GaAs as well as AlGaN/GaN, which are very
powerful devices, have been discussed, for high 3. Asbeck, P. M., et al. “GaAlAs/GaAs heterojunction bipolar
speed operation, based on the high mobility of the transistors: Issues and prospects for application.” IEEE
electrons in the 2D electron-gas. Both high speed Transactions on Electron Devices 36.10 (1989): 2032-
and high voltage devices can be achieved using 2042.
the AlGaN/GaN devices, which are normally ON.
However, these normally ON devices can be used 4. Mishra, Umesh K., et al. “GaN-based RF power devices
in conjunction with low voltage silicon MOSFET in and amplifiers.” Proceedings of the IEEE 96.2 (2008): 287-
the cascode connection mode with the normally ON 305.
HEMT device to ensure that the device turns ON only
when the input voltage is positive. 5. Moon, J. S., et al. “Gate-recessed AlGaN-GaN HEMTs for
high-performance millimeter-wave applications.” IEEE
Electron Device Letters 26.6 (2005): 348-350.

6. Ikeda, Nariaki, et al. “GaN power transistors on Si
substrates for switching applications.” Proceedings of
the IEEE 98.7 (2010): 1151-1161.

REFERENCES

1. Kim, M. E., et al. “GaAs heterojunction bipolar transistor
device and IC technology for high- performance analog
and microwave applications.” IEEE Transactions on
Microwave Theory and Techniques 37.9 (1989): 1286-
1303.

 4

NANOPILLAR ARRAY OF CDS/CDTE THIN FILM
PHOTOVOLTAIC FOR ENHANCED JUNCTION AREA

Murugaiya Sridar Ilango1, 2, Sheela K. Ramasesha1, 2, and Dinesh Kumar2
1Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru.
2Department of Physics, Jain (Deemed-to-be University), Bengaluru. [email protected]

Abstract spectrum, absorption coefficient, cost effective and
simple deposition technique [2]. One of the factors
In this paper, nanopillar based an array of CdS/ limiting the performance of the solar cell photo
CdTe solar cell has been proposed and fabricated voltaic performance is the insufficient absorption and
in a view of increasing the junction area. CdS/ collection of the generated carriers. Over the past
CdTe nanopillars pattern have been designed couple of years, lot much work has been carried out
using electron beam (E-beam) lithography and on nanowire and nanopillar based solar cell structures
deposited using RF magnetron sputtering. Device as enhanced carrier collection and optical absorption
electrical characterization has been carried out can enable more efficient solar cell compared to planar
to measure I-V characteristics and electrical structure[4]. A nanopillar based an array of CdS/CdTe
parameters of interest. From the measured solar cell has been proposed and fabricated in this
data, parameters of interest such as short circuit paper. The device electrical characterization has been
current, open circuit voltage, conversion efficiency carried out to extract the parameters of interest from
and fill factor has been found to be 1.14e-08, 0.042 the measured Current-Voltage (I-V) characteristics.
V, 0.08% and 33% respectively.
2. Design and fabrication
Keywords: Nano-pillar-based photovoltaics solar cells
nanowires The fabrication of the device structure starts with the
growing 1 micron thick oxide layer on the silicon
1. Introduction wafer using diffusion furnace. Firstly, patterns for
the bottom electrode has been created using electron
Solar energy abundant though, yet least harvested. beam lithography followed by the fabrication of
Many state of the art solar cell device structures the CdTe nanopillars. A layer of n-type material of
and materials have been proposed, each one of them CdS with 50nm thickness has been grown on CdTe
have different pros and cons [1]. Among various nanopillars using RF magnetron sputtering. Then top
types of photovoltaic solar cell structures, CdS/ electrode of Au with thickness 20nm is deposited
CdTe solar cell has found wide acceptance due to an for CdS. Figure 1 shows the device structure of the
appropriate energy band gap required for visible solar proposed device.

Fig. 1. Cross-sectional schematic of the textured thin film PV

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Advances in Semiconductor Materials and Device Technologies

3. Results and discussion CdS/CdTe thin film solar cell. The nanopillar
diameter has been found to be 290 nm with a
a) Morphological characterization: gap of 70 nm. The stack shows Au contacts at
the bottom and CdTe above the Au nanowalls
Figure 2 shows the Field emission scanning and CdS which is sputtered using RF sputtering.
electron microscopy (FESEM) image of textured

Fig. 2. SEM image for morphological characterization

b) IV characteristics: simulator from Albet. The efficiency has been
found to be 0.08% which can be improved by
Figure 3 shows the IV curve of the fabricated optimizing the operational parameters of the
nanopillar based CdS/CdTe solar cell under device. The open circuit voltage, short circuit
illumination. Electrical characterizations of the current, and a fill factor has been found to be
device have been carried out using IV solar 0.042 V, 1.14e-8A and of 33 % respectively.

Fig. 3. IV characteristics of fabricated device

4. Conclusion promising results. Besides, the proposed concept
has also been studied through the detailed numerical
CdS/CdTe nanopillar solar cell has been fabricated simulation using TCAD simulator Silvaco in order to
with the help of e-beam lithography and characterized get a further insight of the implemented concept.
electrically. The extracted parameters of interest from
the measured I-V characteristics have shown very

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Advances in Semiconductor Materials and Device Technologies

REFERENCES 3. D.M. Meysing et al.,“Chemical and mechanical
techniques enabling direct characterization of the cds/
1. Jae Ho Yun, EunSeok Cha, Byung Tae Ahn, HyuckSang cdteheterojunction region in completed devices”,
Kwon, Essam A. Al-Ammar, “Performance improvement Proceedings of the 42nd IEEE Photovoltaic Specialists
in CdTe solar cells by modifying the CdS/CdTe interface Conference, New Orleans, LA, pp.1–6, 2015.
with a Cd treatment”, Elsevier Current appl. Phys., vol. 14,
pp. 630-635, 2014. 4. J.M. Kephart, R. Geisthardt, W.S. Sampath, “Sputtered,
oxygenated CdS window layers for higher current in CdS/
2. Daniel M. Meysing et al., “Evolution of oxygenated CdTe thin film solar cells”, Proceedings of the 38th IEEE
cadmium sulfide (CdS:O) during high- temperature CdTe
solar cell fabrication”, Solar Energy Materials & Solar Photovoltaic Specialists Conference, pp. 854–858, 2012.
Cells, vol. 157, pp.276- 285, 2016.

 7

EFFECT OF SUBSTRATE TEMPERATURE ON THE QUALITY

OF INSB THIN FILMS

A.G. Kunjomana and Bibin John* Research Centre, Department of Physics,
Christ (Deemed-to-be University), Bengaluru -560 029, Karnataka.
Email - [email protected], Mobile No: 9449645957

Abstract applications, such as night vision, chemical sensing,
counter measures, and industrial process control.
The influence of substrate temperature during the Several researchers have deposited InSb thin films on
crystallization of indium antimonide thin films semi-insulating substrates such as gallium arsenide,
was investigated systematically by employing the indium phosphide, silicon, etc. and observed a large
facile thermal evaporation process. The deposited lattice mismatch of the prepared sample with these
samples were characterized to evaluate the substrates [5-9]. Economically viable glass has widely
structure, purity, composition and morphology been used as a flexible substrate for the fabrication
utilizing suitable techniques. The impact of oftwo-dimensional materials. However, adequate
heat treatment resulted in the improvement of results have not been reported on the growth of III-V
crystallinity, which has been thoroughly examined materials on glass surfaces that are highly transparent in
by X-ray diffraction method. Grain growth the mid-infrared spectral region. Hence, in this present
featuresof the two dimensional structures were work, the most popular and cost effective thermal
observed with the help of optical and scanning evaporation technique has been utilized for the growth
electron microscope, whereas their stoichiometry of monophase InSb thin films on glass substrate.
was confirmed by energy dispersive analysis using
X-rays. 2. Experimental Description

Keywords: Indium antimonide, Thermal evaporation, Stoichiometric InSb compound was synthesised by
Substrate temperature, Stoichiometry the homogeneous blending of high pure indium and
antimony in the ratio 50:50 in the muffle furnace
1. Introduction attached with a rotation mechanism. The constituent
elements were filled in a 10 cm long and 1 cm inner
The demand of photodetectors has stimulated research diameter quartz ampoule. It was sealed under the
on innovative practices for the production of large area diffusion vacuum (10-6mbar) and slowly heated
and perfect modules of semiconducting crystalline to stabilize at a temperature of 600°C for 48h. The
layers. Group III-V based compounds are popular as ampoule was rotated periodically (60 rpm) to ensure
the building blocks of electronics and IR detection complete reaction and homogeneity throughout the
devices due to their tunable physical properties. Owing mixture. The source material was powdered and
to its high electron mobility, indium antimonide (InSb) loaded in a molybdenum boatinside the deposition
compounds can be used in infrared imaging systems, chamber of Hind High Vacuum system (Model:
space communication, magneto-resistive sensors and 12A4D). The coating procedure was performed under
high-speed photodetectors [1–3]. The high values of a vacuum ~ 10-6mbar, which facilitates mean free
absorption coefficient and well-established fabrication path of molecules and avoids oxidation. High tension
techniques of InSb make it an important alternative to cleaning by nitrogen ions was executed to remove
the modern HgCdTe for mid-infrared photodetection the impurities on the substrate surface. Thus, the two
[4], which can be applied to a wide range of technical dimensional structures of InSb were grown at various

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Advances in Semiconductor Materials and Device Technologies

substrate temperatures ranging from 50-250°C. attenuating grain boundaries. The influence of ST
Surface morphologies of the films were characterized was investigated within the range, 50-250 °C. When
with anoptical (METAGRAPH-I) and integrated substrate temperature was intentionally increased,
scanning electron microscope (Model: ULTRA 55) enhancement of particle size has observed due to the
coupled with energy- dispersive analysis by X-rays coalescence of small crystallites[9]. X-ray diffraction
(EDAX). The material quality of the grown InSb method was used to probe the structure and purity
films was investigated by X-ray diffraction (XRD), of the prepared samples, which confirmed cubic
(Model: X’Pert PRO) using Cu K radiation source structure with lattice constant, a =l 6.473 Å. The
of wavelength =1.540 Å with the scanning angle XRD patterns of the as-deposited and 250 °C InSb
(2θ) between 50 to 700. thin films are depicted in Fig.1.

3. Results and Discussion The reflections correspond to the (111), (220) and
(311) planes matched well with the results reported by
The as-grown thin films of InSb were found to be Udayashankar and Bhat [10]. The recorded profile at
amorphous, due to the insufficient energy of the 250 °C revealed the absence of other peaks justifying
particles to form an ordered structure. Therefore, the formation of monophase indium antimonide
the structural properties of deposited films were fine structure.
tuned by varying the substrate temperature (ST) for

Fig. 1. XRD spectra of InSb thin films deposited at (a) 50 °C and (b) 250 °C.

Chemical composition of the deposited InSb thin film stoichiometricindium antimonide thin films. Grain
at 250 °C, exhibited uniform elemental distribution growth engineering of the samples was systematically
throughout the surface. Table 1 displays the atomic analyzed with the aid of optical and scanning
percentage of the 2D structure, where the peaks electron microscopes. Fig. 2 shows the SEM and
correspond to the elemental proportion of In:Sb opticalimages of InSb thin film coated at 250°C with
(49.47:50.53), which is close to the stoichiometric a nearly smooth surface, which enabled to investigate
molar ratio of InSb. The computed result established the transformation from polycrystalline to crystalline
the right experimental protocol for the synthesis of nature of the sample.

Table 1: Atomic percentage of elements in InSb thin film

Elements Experimental (at. %) Standard (at. %)
In 49.47 50.00
Sb 50.53 50.00

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Fig. 2. (a)SEM micrograph and (b) optical image of InSb thin film deposited at 250 °C.

4. Conclusion 2. D.L. Partin, L. Green, J. Heremans, J. Electron. Mater. 23
(1994) 75.
Indium antimonide thin films prepared by thermal
evaporation technique at various deposition 3. Kimukin, N. Biyikli, E. Ozbay, J. Appl. Phys. 94 (2003)
temperatures on glass substrate have been explored 5414.
systematically. The XRD and EDAX measurements
confirmed the formation of monophase InSb thin 4. J.Wu, D.Shao, V.G.Dorogan, A.Z.Li, S.Li, E.A.DeCuirJr,
films at 250°C. Microscopic analysis revealed the M.O.Manasreh, Z.M.Wang, Y.I. Mazur and G.J.Salamo,
evolution of polycrystalline to nearly crystalline Intersublevel infrared photodetector with strain-free GaAs
surface of the two dimensional structure. Thus, the quantum dot pairs grown by high-temperature droplet
research findings justified the crystallinity of InSb epitaxy, Nano letters. 10(2010) 1512.
films within crease in substrate temperature within
the range, 50-250°C. 5. B.V. Rao, T. Okamoto, A. Shinmura, D. Gruznev, M.Mori,
T. Tambo, C. Tatsuyama, Appl. Surf. Sci. 159(2000) 335.
ACKNOWLEDGEMENTS
6. S.D. Parker, R.L. Williams, R. Droopad, R.A.
The authors are thankful to the research team of Stradling,K.W.J. Barnham, S.N. Holmes, J. Laverty, C.C.
Centre for Nanoscience and Engineering, Indian Phillips,E. Skuras, R. Thomas, X. Zhang, A. Staton-Bevan,
Institute of Science, Bengaluru for their assistance to D.W.Pashley, Semicond. Sci. Technol. 4 (1989) 663.
perform various characterizations.
7. M. Mori, Y. Nizawa, Y. Nishi, K. Mae, T. Tambo,
REFERENCES C.Tatsumaya, Appl. Surf. Sci. 159 (2000) 328.

1. P.E. Thompson, J.L. Davis, J. Waterman, R.J. Wagner, D. 8. E. Michel, J.D. Kim, S. Javadpour, J. Xu, I. Ferguson,
Gammon, D.K. Gaskill, R. Stahlbush, J. Appl. Phys. 69 M.Razeghi, Appl. Phys. Lett. 69 (1996) 215.
(1991) 7166.
9. K. Kanisawa, H. Yamaguchi, Y. Hirayama, Appl. Phys.
Lett. 76 (2000) 589.

10. M.Tomisu, N. Inoue and Y.Yasuoka, Vacuum. 47(1996)
239.

11. N. K. Udayashankar and H.L. Bhat, Bulletin of Materials
Science. 24(2001) 445.

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OPTICAL AND MICROSTRUCTURAL STUDIES
ON COSO4.7H2O FILLED EPOXY

Shruti S. Devangamath and Blaise Lobo*
Department of Physics, Karnatak University’s Karnatak Science College,
Dharwad 580001, Karnataka, India. *E Mail: [email protected]

Abstract heptahydrate (CoSO4.7H2O), a hydrated transition
metal salt, is incorporated as an inorganic component
Epoxy-CoSO4.7H2O polymer hybrid films were (filler) in the epoxy polymer. The influence of
prepared with easy synthesis method such as inorganic component on optical and microstructural
physical blending with low cost of synthesis. The properties of pristine epoxy polymer is studied by
prepared hybrids with better optical properties various characterization techniques.
and lower band gaps can be possibly used in
optical applications. Due to better mechanical 2. Materials and Methods
properties and induced optical properties, the
prepared hybrids can find use in various other Epoxy polymer used in this work, is a commercial
applications. available two component (resin and hardener;
separately packed) adhesive, which cures at room
Keywords: Epoxy, Cobaltous sulfate heptahydrate, UV- temperature. The epoxy resin is Diglycidyl ether of
Vis spectroscopy, FTIR, SEM bisphenol A (DGEBA) based and the hardener used
is amine based. The inorganic filler, Cobaltous sulfate
1. Introduction heptahydrate pure with molecular weight 281.1 g/mol
was purchased from Himedia laboratories Mumbai.
Epoxies are important thermosetting polymers, which Hybrid organic inorganic material using epoxy and
are formed by the crosslinking reaction between CoSO4.7H2O, was prepared in the laboratory by
resin and hardener. Epoxy polymers are used as a simple and low cost technique such as physical
matrix materials in many polymer composites due blending. Various quantities of filler (0.28 wt. % to
to their appreciable mechanical, thermal, adhesive 5.00 wt. %) were added to a specified amount of
and electrical properties [1]. Physical properties of resin and the mixture was grinded in agate mortar. A
pristine polymers can be effectively tuned by the measured amount of hardener (resin and hardener ratio
addition of various fillers such as transition metal of 5:4) was then added and thoroughly grinded. The
salts, semiconducting particles, which may be in prepared mixture of epoxy polymer and CoSO4.7H2O
the form of particles, fibers, whiskers. Reducing was then casted in the form of thin film on a Teflon
the size of inorganic constituent to that of organic sheet. The casted film was allowed to cure for one
building block leads to the formation of hybrid day at room temperature, in order to get a crosslinked
materials, which are homogeneous mixtures (unlike epoxy polymer hybrids. The prepared epoxy hybrid
that of composites). Hybrid materials are also broadly materials were characterized by UV-Vis absorption
defined as nanocomposites with intimately mixed spectroscopy, Fourier transform infrared spectroscopy
organic and inorganic components [2]. In this work, (FTIR) and Scanning electron microscopy (SEM).
hybrid organic inorganic material is formed by using
epoxy as an organic component. Cobaltous sulfate

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3. Results and Discussion wavelength range of 200-800 nm. Electronic
transition from highest occupied molecular
a) UV-Vis absorption: orbital (HOMO) to lowest unoccupied molecular
orbital (LUMO) on absorption of photon of
JASCO V-670 UV-Vis-NIR spectrophotometer suitable frequency, corresponds to an absorption
was used to study the UV-Vis absorption edge in the absorption spectrum.
properties of the epoxy hybrid materials.
Absorption studies were carried out in the

Fig. 1. Absorbance versus Energy plots, for different FLs of CoSO4.7H2O in epoxy hybrid films
(expressed in weight percentage)

Fig. 1 represents absorbance versus energy plots for 5.05 eV (pure epoxy) to 4.12 eV (FL of 0.56 wt. %).
pure epoxy and epoxy hybrids with various filler Multiple absorptions can also be seen for higher FL
levels (FLs). It can be seen that for FL of 0.56 wt. of 4.44 wt. %.
%, the absorbance has shifted to lower energy (higher
wavelength) region, indicating a possible decrease b) Fourier transform infrared spectroscopy
in the optical band gap of the material. This drastic (FTIR):
decrease in the band gap can be attributed to better
interaction between polymer matrix and filler and also FTIR technique is very efficient, non-destructive
to possible change in the microstructure of pristine technique to study the crosslinking reactions in
epoxy polymer. Band gap (Eg) values were calculated epoxies and also to identify the molecular groups
by famous Mott-Davis equation. Direct forbidden present in the composites and polymer hybrid
energy gap was found to decrease from 5.23 eV (for materials. Thermoscientific’s Nicolet 6700 FTIR
pure epoxy) to 4.16 eV (FL of 0.56 wt. %) and energy instrument was used for FTIR studies. Fig. 2
gap for indirect allowed transitions decreased from represents FTIR spectra of epoxy hybrids.

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Fig. 2. FTIR spectra of pure and filled epoxy hybrids with mentioned
FLs of CoSO4.7H2O in epoxy hybrid films (expressed in weight percentage).

DGEBA based epoxy resin is characterized by the reaction between resin and hardener. Broadening of
presence of FTIR peak due to oxirane ring (the main OH peak at wavenumber of 3500 cm-1, and shift of
feature of epoxy monomer) stretching at 3057 cm-1 carbonyl (C=O) peak to lower wavenumber indicates
and peak at 915 cm-1 corresponds to C-O stretch of interaction between epoxy and CoSO4.7H2O through
oxirane ring. The consumption of these two bands C=O group, with possible formation of hydrogen
in FTIR spectra indicates the cure or crosslink bonds [3].

Fig. 3. SEM images for a) pure epoxy b)0.28 wt. % FL c) 0.56 wt.% FL d) 4.44 wt. % FL

c) Scanning electron microscopy (SEM): This indicates better interaction and influence of
CoSO4.7H2O on epoxy polymer.
Microstructural characterization of prepared epoxy
hybrid materials was carried out by EVO MA18 4. Conclusion
scanning electron microscope. Fig. 3 represents SEM
images of pure epoxy and epoxy hybrid materials. Epoxy polymer, incorporated by CoSO4.7H2O at
It can be seen that surface roughness has decreased various FLs, showed better optical and microstructural
considerably with increase in FL. At higher FL properties. These properties suggest the possible use
of 4.44 wt. %, formation of nano-needles is seen. of material for various optical and optoelectronic
applications.

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Acknowledgements REFERENCES

We are thankful to USIC, KUD, Dharwad for UV- 1. Ramirez, M. Rico, A. Torres, L. Barral, J. Lopez, and
Vis and FTIR facilities. We are thankful to MIT, B. Montero, Epoxy/POSS organic- inorganic hybrids:
Manipal, for use of SEM facilities. First author also ATR-FTIR and DSC studies, Eur. Polym. J., 44, 3035-
acknowledges financial assistance in the form of 3045, 2008.
Vidyasiri fellowship from Govt. of Karnataka.
2. Sanchez, B. J. Lopez, P. Belleville, and M. Popall,
Applications of Hybrid organic-inorganic nanocomposites,
J. Mater. Chem., 15, 3559-3592, 2005.

3. W. Zhang, A. A. Dehghani-Sanji, R. S. Blackburn, IR study
on hydrogen bonding in epoxy resin- silica nanocomposites,
Progr. Nat. Sci., 18, 801-805, 2008.

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DESIGN OF MEMS ACCELEROMETERS FOR WIDE
BAND STRUCTURAL DYNAMIC STUDIES

Nitish Kumar C*, M.S. Giridhar, Ashwini Jambhalikar, Gogulapati Supriya, Bhuvan M.B,
Pratheek T.K. JJohn**, R. Islam and M. Viswanathan
Laboratory For Electro-Optics Systems (LEOS), ISRO, Peenya 1st Stage, 1st Cross, Bengaluru
560058; Indian Institute of Space Science and Technology*,Trivandrum,Valiyamala-695547
Email:[email protected]* [email protected]**

Abstract range, both in terms of amplitude and frequencies.
A single design cannot meet this system level
This paper discusses the design of MEMS based requirement. This paper presents a novel concept of
capacitive accelerometers for structural dynamic having identical sensors but deigned to have various
studies of systems. A satellite undergoing the sensitivity and bandwidth. Certain subsystems need
process of launch and associated events in a rocket low g (few micro g) and low frequency (few tens Hz)
experiences various amplitude and frequencies measurements where as in certain cases it is several
of vibrations. An array of accelerometers can be orders of magnitude. Laboratory for Electro-Optics
used to study the response of various subsystems. Systems (LEOS), ISRO has already demonstrated
Open loop, low weight, low power consuming MEMS based accelerometers with inertial grade
MEMS based accelerometers can be an apt performance in one of the geostationary satellite
choice for conducting this experiment. This paper GSAT19. The satellite has micro-g resolution with
presents the design of bulk silicon micromachined dynamic range of 0.5g and 20Hz bandwidth. The
accelerometers to meet this requirement based product has silicon-on-glass architecture and is
on the experience of proven accelerometer fabricated in house with a qualified process flow. The
indigenously developed at Laboratory For Electro- product is 2 Axis accelerometer in HMC package,
Optics Systems for an Indian satellite. weighing around 25 grams and consuming less than
10 mW power. The product is space qualified as per
Keywords: Accelerometers, MEMS, Sensors, Electro- standard requirements. A circuit giving capacitance to
Optics Systems digital output is also housed in the HMC. This paper
proposes an approach where the basic architecture
1. Introduction and process flow is maintained, but MEMS structures
with various performance specification to meet
MEMS is a technology that in its most general form structural dynamic studies are met. The details of the
can be defined as miniaturized mechanical and electro- design and fabrication plan is also presented in brief.
mechanical elements (i.e., devices and structures) that
are made using the techniques of micro-fabrication. 2. Working Principle
MEMS accelerometers are very attractive for space
navigation, automobile applications, such as airbags, An accelerometer is a sensor that measures the
automatic guidance because of its miniaturized physical acceleration experienced by it. Conceptually,
size, weight, cost and power advantages. Apart an accelerometer behaves as a damped mass on a spring.
from its traditional applications, it can be used When the accelerometer experiences acceleration, the
in space applications also to study the dynamic mass is displaced in response to that the displacement
response of satellite subsystems, where the response is then measured to give the acceleration. In open loop
of the various locations of a satellite to different system capacitive techniques are commonly used to
mechanical. Events associated with launch, stage convert the mechanical motion into an electrical signal.
separation, and injection to orbit can be studied. The Capacitive accelerometers performance is superior
response of various subsystems will be over a wide in low-frequency range and they can be operated in

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servo mode to achieve high stability and linearity.
The principle of working of an accelerometer can be (3)
explained by a simple mass (m) attached to a spring
of stiffness (k) that in turn is attached to a casing, as (4)
illustrated in Fig 1. The mass used in accelerometers As Cest cannot be zero for all values of them
is often called the seismic mass or proof-mass. The (ms2+cs+k)=0 called as auxiliary or characteristic
system is represented by spring-mass dashpot system equation of the system. The solution to this equation
includes a dashpot to provide the desired damping for values of is
effect. The dashpot with damping coefficient (c) is
normally attached to the mass in parallel with the (5)
spring. When the spring-mass a system is subjected This equaton 5 is a standard form for any second order
to linear acceleration, a force equal to mass times transfer function. [6] Comparing Equation 3 with the
acceleration acts on the proof-mass, causing it to equation 5 we will get the following equations
deflect. This deflection is sensed by a suitable means
and converted into an equivalent electrical signal.
The inherent damping phenomenon helps to stabilize
the response of the system.

From the stationary observer’s point of view, the sum
of all forces in the z direction is

(6)

(7)

(8)
Where, is natural frequency, k. spring constant,
is damping ratio

A. Steady state performance

Fig. 1. Schematic of an accelerometer [7] In the steady state that is with the excitation acceleration
amplitude ‘a’ and frequency ‘F’the amplitude of the
(1) response is constant and is a function of excitation
acceleration amplitude ‘a’ and frequency F. Thus for
Where, m is mass of the proof-mass, x, relative static response F=0, the deflection amplitude is [7]
movement of the proof-mass with respect to frame,
c, damping coefficient, k, spring constant, F, force (9)
applied. The equation of motion is a second order linear
differential equation with constant coefficients. The (10)
general solution x(t) is the sum of the complementary
function XC(t) and the particular integral XP(t) Here the Mechanical Sensitivity “S” of an
Accelerometer is defined by,
(2)
The complementary functions satisfy the homogeneous (11)
equation.

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3. Sensor Architecture in the other two. The pairs are connected in parallel
in the readout circuit. The arrangement is configured
The wafer consists of the active proof-mass, which as a differential sensing capacitors at the readout end.
moves as a function of the applied acceleration When there is a deflection the associated change in
thereby causing the change in capacitance. The capacitances is denoted by equations 12 and 13.
proof-mass is supported on all four sides by beams.
The proof-mass exhibits in-plane movement and Where N1 and N2 are the number of electrode pairs
remain parallel to electrodes at all accelerations. The A is the area of overlap, d1, d2 distance between the
proof mass is provided with comb electrodes, which electrodes, x, displacement of the sensor.
acts as movable electrodes in a capacitor assembly.
There are fixed electrodes interdigitated with these 4. Sensor Design
movable electrodes. As the proof mass displaces,
the gap between the electrodes changes and hence The idea is to fabricate sensors with varying dynamic
the associated capacitance also changes. To avoid range on a single wafer through a single fabrication
the collision between movable and fixed electrodes process flow. The proposed design accommodates
due to large displacements a mechanical stopper sensors coded as D1GR to D5GR indicating the
is provided. Differential capacitance transduction design for its dynamic range in g. Each design has
method is selected as it offers the advantages of different mechanical and electrical sensitivity and
low-temperature sensitivity, higher transduction bandwidth. This is due to the straight forward fact
efficiency. Capacitive sensing is also known for its that the beams are fine tuned for various g levels.
high accuracy and stability. Capacitive accelerometers This leads to varying stiffness and thereby resonant
are also less prone to noise and variation with frequencies. As a thumb rule, the bandwidth of the
temperature, typically dissipate less power, and sensor is assumed to be 20% of its first resonant
can have a larger dynamic range of operation and frequency. Each sensor undergoes the same fabrication
linearity by a closed loop operation. In the current process and each has the same readout electronics
design, the electrodes are distributed into four arms configuration. The design deals with the open loop
as shown in Figure 2. Each arm has 11 movable and accelerometers. For the sensors which are having 1g and
12 fixed electrodes and has a dead capacitance of 2g range are having folded beams as the range of the
around 8.5 pF. The placement of electrodes ensures sensor gets increased from 3g to 5g the folded beams
them to operate in a differential sensing mode. That have been modified in to straight beams. This is because
means, for a given deflection of the proof mass along the modes of frequencies for the design observed to be
a given direction, the capacitance associated with two close by, thereby increasing the cross axis sensitivity of
arms will increase from its dead value and decrease the accelerometer, which is an undesired parameter.

Fig. 2. Schematic of the proposed accelerometer

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I. A. Modelling of the Beam L2 does not have any effect because of its shorter
The general expression for stiffness of beam plate vertical length we neglect it. Stiffness constant
structure with architecture shown in Figure 2 is given of the beam is found by the equation.
by equation 14. The stiffness is tuned by varying the
beam dimensions. We propose variation in the nature 2) Straight beam: To accommodate higher range
and length of the beam as discussed below. sensors and to avoid cross-axis sensitivity the
folded beams are modified to straight beams and
(14) its length is varied and keeping the remaining
Where, Y is the Young’s Modulus of material of beam parameters same.
1) Folded beam: In design D1GR and D2GR
The detailed FEM analysis of the models have
the beams are folded in shape of ”U” to have been done and results are shown in Figure and
relatively larger mechanical sensitivity. Since it Table I given below. The percentage error for
is a folded structure the effective length can be D1GR and D2GR designs are more because of
taken as L. And dependence on L1 and L2 can the approximation of the effective length. The
be mathematically represented by the equation required design is achieved just by changing
14. the length of beams keeping the remaining
parameters same.
Fig. 3. (a) Folded beam (b) Straight beam
The design assumes same dimensions for proof mass,
width and depth of the beams and gap between the
electrodes. The proof mass is 5×3×0.27mm. The
beam is 73µm wide and fixed and movable electrodes
are 60µm and 55µm respectively. The thickness is
200µm. The gap between the electrodes is designed
to be 8µm. The variation in length for various designs
are summarized in Table II.

(15)

Fig. 3. Analysis results for various designs a) DIGR b) D2GR c) D3GR d) D4GR e) D5GR

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5. Fabrication Process Flow process using the machine from SPTS. High aspect
ratio etching is used to define the comb electrodes. The
The structures are fabricated using the matured bonding of silicon wafer to glass is carried out using
fabrication process flow developed by LEOS anodic bonder from AML. Aluminium contacts are
which has been already used in the development defined on the wafer by sputtering with Nanomaster
of accelerometer in the GSAT19 mission. The Sputter system. The patterned wafer is annealed at
structures are fabricated from double side polished 475ºC to make the contact linear and low resistance
100 mm Diameter, low resistivity silicon wafer. in nature. The devices are singulated by trenching the
The starting thickness is 380_m. The support wafer wafer stack using dicing machine from ADT. After
is 500_m thick, borosilicate glass having both sides every stage of silicon etching, the photoresist that is
polished to optical finish. We are using three masks to used as the masking layer is removed using plasma
realize the accelerometer structure with five levels of ashing system from PVA Tepla. The fabrication
photolithography. The key process step in silicon wafer process flow is schematically shown in Figure 5.
processing is the dry etching with standard Bosch

6. Performance Evaluation and Integration respectively. The sensor read out electronics are
To Readout housed in a hybrid micro circuit (HMC) and
hermetically sealed in 1 atm Nitrogen ambient. The
The change in capacitance is read out using a device is space qualified at MEMS component level
capacitance to digital converter IC. The electronics and package level. Figure 4 shows the space qualified
converts change in capacitance from the sensor to accelerometer package developed at LEOS. The
serial digital output. Each sensor will employ the accelerometers are calibrated in standard facility
same readout electronics and packaging scheme. installed in our Lab. The devices proposed in this
The electrical sensitivity of design D1GR to D5GR paper will also undergo similar processes before
are 4pF/g, 2pF/g, 1.3pF/g, 1pF/g and 0.8pF/g inducting for space applications in future.

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Fig. 4. a) 2 axis MEMS accelerometer developed at LEOS ISRO, b) Open view

Fig. 5. Fabrication process flow for realizing accelerometer sensor structure at LEOS

7. Conclusion Pranab Kumar ”MEMS capacitive accelerometers”,
Sensor Letters, Vol(5):471–484, 2007.
The paper presents the design process adopted for
realizing accelerometers for structure level dynamic 3. Kemp, Christopher J and others ”ISAAC: integrated
studies in satellites. A generalized approach to realize silicon automotive accelerometer”, Sensors and Actuators
accelerometers with wide range of sensitivities and A: Physical, Vol(54):1–3, 1996.
bandwidth is discussed. It will employ a proven
process flow for fabrication, readout electronics, 4. Instrumentation-Electronics. (2018). M E M S
packaging and space qualification tests for reliability Accelerometer-Acceleration Transducer,Sensor,Working,T
assurance. echnology. [online] Available at:

REFERENCES 5. h t t p : / / w w w. i n s t r u m e n t a t i o n t o d a y. c o m / m e m s -
accelerometer/2011/08.
1. Benmessaoud, Mourad and Nasreddine, Mekkakia Maaza,
”Optimization of MEMS capacitive accelerometer”, 6. Kempe, V. (2011). ”Inertial MEMS”. Cambridge:
Microsystem Technologies, Vol(19):713–720, 2013. Cambridge University Press.

2. Biswas, Karabi and Sen, Siddhartha and Dutta, 7. [online] Available at: http://www.kves.uniza.sk/kvesnew/
dokumenty/DREP/Filters/2nd.

8. S h o d h g a n g a . i n f l i b n e t . a c . i n . ( 2 0 1 8 ) . [ o n l i n e ]
Availableat:http://shodhganga.inflibnet.ac.in/bitstream/
10603/2272/8/08.

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STUDY OF THE EFFECT OF ELECTRON IRRADIATION
ON MOSFET FOR SPACE APPLICATIONS

Sujatha R 1*, Abdul Rehman Khan2, M. Ravindra2 and R. Damle1
1 Department of Physics, Bangalore University, Bengaluru-560 056 2 ICG, ISRO Satellite Centre,
Vimanapura, Bengaluru-560 017
1* Corresponding author. Tel: +91 99865 88340, E-mail: [email protected]

Abstract degradation. The damage or degradation may be
permanent or transient. The degradation behaviour
The space environment is hostile to most is a complex process and is dependent not only on
semiconductor electronic devices and components the nature of the device but also on the radiation
used for space applications. The radiation generally characteristics viz., dose, dose rate, species and
encountered in space is α, β, γ, x-ray, energetic the energy of radiation. The study of the effect of
electrons, protons, neutrons and ions of various ionizing radiation on semiconductor devices has thus
kinds. Especially the Van Allen Belts consist of high become very important to have an understanding of
energy electrons which are in continuous motion. the physical mechanism of the damage process and
Satellite systems operating in Low Earth Orbits to assess the device performance when they need to
(LEO) are prone to get exposed to high energy be operated in the radiation environment. Excellent
electrons. This paper describes the effect of electron literature is available on effects of radiation viz.,
beam irradiation on MOSFETs planned for space x-rays, neutrons, electrons, protons, heavy ions on
applications. The devices selected for the study are variety of semiconductor devices including Bipolar
2N6768 n- channel MOSFETs (JANTXV) procured Junction Transistors (BJT’s), integrated devices and
from ISAC, Bengaluru. The decapped MOSFETS Complimentary MOS (CMOS) devices. However,
are exposed to a beam of electrons for various doses the basic mechanism of radiation-semiconductor
ranging from 50 Gy to 10 KGy in the electron energy interaction leading to device degradation is not
range 7 – 10 MeV using the electron accelerator yet completely understood. While the study of
facility at RRCAT, Indore. Pre and post- irradiation radiation induced effects in CMOS and IC’s is more
measurements of the electrical characteristics are complex, the study on 3- terminal semiconductor
undertaken to investigate the electron induced device device (BJT/ MOSFET) can provide useful insight
degradation and damage. The present investigation into the mechanism of degradation [1]. Many of
reveals that there is a substantial increase the the BJTs and MOSFETs which are not available in
leakage current and the transconductance displays radhard (radiation hardened) version, are still being
considerable reduction when the devices are exposed used in space systems. It is therefore essential to
to electrons. This increase in leakage current can characterize these devices for radiation induced
have significant impact on device performance in a effects. Further, investigations on radiation- induced
radiation environment. effects on devices indigenously made in India, to our
knowledge, have not been fully carried out. It is thus
Keywords: Radiation hardened, MOSFET, Threshold important to establish radiation-induced response of
voltage, Transconductance, Mobility these devices in comparison to other vendor’s parts
of the similar family. Further, compared to BJTs
1. Introduction rather little literature is available on radiation damage
studies in MOS devices and therefore we have taken
When semiconductor electronic devices are exposed up the study of MOSFETs for radiation testing. It is
to radiation (viz. -rays, X-ray, electrons, .neutrons, known that radiation damage mechanism in MOS
protons or heavy ions, etc.) they may undergo severe

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devices is quite different from that in BJTs and hence 3. Result and Discussions
it is essential to understand the basic mechanism of
device degradation and damage in MOS structures. The dominant mechanism of the interaction of
the electrons with semiconductors is to produce
2. Materials and Methods atomic displacement which can have serious impact
on electrical characteristics. MOS (Metal oxide
The metal oxide field effect transistor (MOSFET) semiconductor) devices are the most sensitive of
is an important device in microprocessors, memory all semiconductor devices to radiation showing
circuits, ICs and mainframe computers of space considerable degradation even for a relatively low
systems. However, there appears to be rather little dose of exposure to high energy electrons. The energy
studies on radiation induced parametric degradation dissipated by electrons in semiconductors is sufficient
of MOSFETs. Such radiation response data and to displace silicon atoms and cause a shift in the
radiation tolerance assessment is quite important threshold voltage and leakage current.
especially when the devices need to be operated
in a radiation rich environment such as in space. a) Shift in the threshold voltage
Hence in collaboration with ISRO Satellite Centre
(ISAC, Bengaluru), we have undertaken a program When the primary electrons reach the gate oxide
to study the radiation induced effects in some of a MOSFET, it generates electron-hole pair.
selected MOSFETs which are being used for space The electrons and holes are transported by the
applications. The devices selected are 2N6768 electric field. Since the electron possess higher
n- channel MOSFETs (JANTXV) procured from mobility than holes, the latter drift slowly and
component division of ISAC. Eight devices (all with are trapped in the gate oxide. For positive gate
same date code) are collected and pre irradiation voltage, holes move to the Si-SiO2 interface and
measurements of electrical characteristics viz., are trapped. On the other hand, for a negative
threshold drain to source voltage (VDS), leakage gate voltage, holes move to the metal side
current (ID), forward and reverse resistances, output andget trapped. In absence of electric field under
characteristics, transfer characteristics and source zero gate voltage, the holes diffuse isotropically
to drain diode characteristics are measured using [2]. The sub-threshold I-V characteristics(output
TESEC semiconductor measurement system in ISAC characteristics) of n-channel 2N6768 for various
Bengaluru. All the devices belonging to the same irradiation dose are shown in Fig. 1. As seen
date code have identical electrical characteristics. from the graph, drain current increases as the
One device is kept as the control device and the rest electron dose increases for a given value of
seven devices are decapped and exposed to a beam VDS. Increase in drain current with dose may
of electrons for various irradiation doses utilizing the be due to change in gate threshold voltage of the
electron irradiation facility available in Raja Ramanna MOSFET.
Centre for Advanced Technology (RRCAT), Indore.
The electron accelerator at RRCAT is operated in For n-channel power MOSFET, the gate
the energy range 7MeV – 10MeV at a controllable threshold voltage becomes negative due to
power level up to 3kW. The dose rate is 10Gy per radiation induced positive charges (holes)
second. Alanine EPR dosimeter is used for precise dominating in the oxide traps and interface traps.
dose measurements. Each of the decapped device is The threshold voltage shift is given by
exposed to a dose of 50Gy, 100Gy, 200Gy, 500Gy,
1 KGy, 5 KGy and 10 KGy respectively. The post ∆VTH= (q /COX ) ∆Nit (1)
irradiation electrical characteristics are measured to
investigate the extent of radiation degradation and where q is the charge, ∆Nitis the change in
damage. electron-hole pair concentration in the Si-
SiO2 interface and COX is the capacitance per
unit area. ∆Nitin turn depends on thenumber
of electron hole pairs produced per dose, the
probability of electron hole recombination,

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incident electron radiation dose and the number of measurement system as a function of electron
interface trapped charges [3]. The Gate threshold dose is represented in the Fig. 2, which displays
voltage measured using TESEC semiconductor a considerable degradation.

Fig. 1. Output Characteristics: Drain Fig. 2. Variation of Gate threshold voltage
Current versus Drain-Source voltage with electron dose for various electron dose

b) Increase in the sub threshold current

The off-state current in MOSFET is the current current can be critical when the transistor is used
which flows from drain to source when gate as a switch. Fig. 4 shows the variation in the ON
to source voltage is zero and is referred as the state drain current with drain to source voltage
leakage current (sub threshold current). Leakage (transfer characteristics) for various doses.
current measured as a function of electron dose Significant changes in output characterizes are
is shown in the Fig. 3. The increase in leakage also observed due to electron induced trapped
current of the device is caused by the shift in the charges.
gate threshold voltage. The increase in leakage

Fig. 3. Variation of Leakage Fig. 4. Transfer Characteristics – Plot between

current with dosage Drain to Source Voltage and ON Drain Current for

various dosage

c) Decrease of Mobility and Transconductance

The degradation in the mobility of charge (2)
carriers (electrons) after irradiation is related to
increase of interface traps, since the conduction

of MOS transistor is due to carrier motion close where µo is pre-irradiation mobility, ∆Nit is the

to silicon oxide interface. The post-irradiation increase of the interface traps and α is a parameter

mobility can be expressed by the following whose value depend on the manufacturing

empirical formula

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Advances in Semiconductor Materials and Device Technologies

technology of the device. The degradation transistor is used as a switch. The transconductance
of the mobility will lead to degradation in of the device is also found to decrease which may
transconductance since transconductance (gm) lead to lowering of the driving capacity of the device.
is proportional to the mobility (µ) in the linear
region [4]. Transconductance measurement Acknowledgement
made after electron irradiation is shown in Fig.
5. The decrease in transconductance would lead The authors thank Mr.V C Petwal of RRCAT, Indore
to decrease the driving capability of the device. for providing e-linac electron irradiation facility for
conducting the experiment and also Mr. Vijay Pal
for his assistance during the experiment. The authors
thank Ms. Vidya of ISAC, Bengaluru for her help
during TESEC measurements.

REFERENCES

1. Y. H. Lho K Y Kim, “Radiation Effectson the Power
MOSFET for Space Application” ETRI Journal, 27 (4),
449-452, 2005.

Fig. 5. Variation of Transconductance of MOSFET with 2. Yee-Chia Yeo, Tsu-Jae King and Chenming Hu “MOSFET
electron dose gate leakage modelling and selection guide for alternate
gate die-electrics based on leakage consideration”. IEEE
4. Conclusion transaction on Electronic devices, 50(4), 2003.

3. High energy electron induced gain degradation in bipolar
junction transistors, S.R. Kulkarni, M. Ravindra, G.R.
Joshi and R. Damle, Nucl. Instr. Meth. B, 251, 157-162,
2006.

The space grade power MOSFET 2N6768 when 4. Jian- Guo Xu, Fang Lu and Heng – Hui Sun, Phys. Rev B,
38, 3395-3399, 1998.
exposed to high energy electrons displays increase in

the leakage current which may be critical when the

 24

SYNTHESIS AND CHARACTERIZATION
OF GRAPHENE DERIVATIVES

Aparna V. Nair and Manoj B
Department of Physics, Christ (Deened-to-be University), Bengaluru-560029, Karnataka, India.
E-Mail:[email protected], Mobile: 09497288156

Abstract to semi-conductor. The valence band and conduction
band in graphene overlaps which makes it an effective
Functionalization of graphene alters the conductor, which also hinders it from wide range of
properties of graphene and hence it can be used applications. This limitation can overcome by using
for numerous applications. Fluorographene the method of functionalization of graphene.
(FG) is obtained from GO through one step
hydrothermal treatment by adding DAST. The In the present study, functionalization has been done
obtained samples are characterized by using FTIR, for graphene. Graphene oxide (GO) is synthesized
XRD, SEM and impedance analysis. The chemical from graphite powder by modified hummers method.
structure is elucidated by Fourier transfer infrared Graphene oxide contains a range of reactive oxygen
spectroscopy (FTIR). The peak at 1216 cm-1 and the functional groups, which renders it as a good candidate
shoulder at 1312 cm-1 are ascribed to the stretching for aforementioned applications through chemical
vibration of covalent C–F bonds and C–F2 bonds. functionalization. FG is prepared by hydrothermal
Surface morphology is observed in both GO(leafy approach. DAST (Di ethyl amino sulphur tri fluoride)
structure) and FG(rocky structure). Impedance is added to GO using hydrothermal method for the
analysis studies shows the dependence conductivity of preparation of Fluorographene.
samples with variation in frequency. The results of
structural, morphological and electrical properties 2. Materials and Methods
of both Graphene oxide and fluoro-graphene shows
the potential utility of these samples as electronic/ a) Preparation of Graphene Oxide:
electrochemical applications.
3g graphite powder is added to 70 ml
Keywords: Graphene oxide, XRD, FTIR, SEM H2SO4(98%), in continuous stirring in an ice
bath for 1 hour. KMnO4 (9g) is then added step
1. Introduction by step to the above mixture slowly within half
an hour while maintaining the temperature at
Graphene is fantastically strong, very light, high 20˚C for 2 hours. Afterwards the whole beaker
surface, high volume, light, stable, conducting containing the sample is kept at 40˚C in oil
material, which is extremely flexible (20% more bath with vigorous stirring for 30 minutes.
stretchable than its original length), conducts heat Then deionised water (150 ml) is added within
and electricity better than carbon, absorbs only 2% 10 minutes with further stirring for 15 minutes
of light falling on it. Notable properties of graphene at 95˚C. 500 ml of deionised water is added
include Ultra high theoretical specific surface area, further and 15 ml H2O2 (30%) is mixed slowly.
exceptional charge carrier mobility, high thermal Further filtration and washing with 1:10 aqueous
conductivity and high optical transmittance. The .solutionof HCl(250ml) is carried out with an
vast field of semiconductors and electronics needs an addition of 600ml deionised water. Sample was
alteration in the property of graphene from conductor kept for Dialysis for 1 week. 1.2 l deionised
wateris added and kept for overnight stirring

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Advances in Semiconductor Materials and Device Technologies

followed by sonication for 30 minutes. Finally 3. RESULTS AND ANALYSIS:
the sample is separated by centrifugation at
10000rpm for 45 minutes and Vacuum drying. a) XRD Analysis:

b) Preparation of Fluorographene: The obtained products are characterized by
X-ray analysis and is presented in Fig.1. The
Preparation of fluorographene is done by XRD of GP(graphite powder) shows peaks
hydrothermal method.0.15 g of GO is added located at 26.62 (d=3.348 Å) corresponding to
to 150 ml of deionised water in a 250ml flask. the 002 reflection[1][2][3]. The XRD profile of
Kept for overnight vigorous stirring. 5ml DAST graphene oxide shows the proper shift of (002)
is added dropwise at 0˚C within 10 minutes. The peak from 26.625 to 11.314 (7.82 Å) which
mixture is kept for ultra-sonication for 6 hours shows oxidation (functionalization) has been
and stirred for three days. 100ml methanol is done successfully or graphite is fully oxidised
added for quenching. to graphene oxide.[2][3][4][5]FG shows a
broad reflection peak at 2Ө=10.49o owing to
the incorporation of fluorine to graphene oxide
matrix.[6][7]

Fig. 1. X-ray analysis of the synthesized graphene derivatives

b) FTIR Analysis: was produce in acidic phase which proved the
presence of carboxylic acid in structure. The
The functional groups of the synthesized readings 1717 cm−1, 1220 cm−1 and 1050 cm−1
graphene derivatives were identified by the are signified to C=O and C-O stretching due
FTIR spectroscopy (Fig.2). Graphene oxide to carbonyl groups in the product.[4][8][9].
spectrum (spectrum (a)) shows different type Chemical structures of FG were investigated by
of oxygen functionalities peaks which are FT-IR spectra (Fig. 2). The absorption peak at
attributed to O-H stretching, C=O stretching, 1602 cm-1 is assigned to the stretching vibration
and C-O stretching. The broad peak at 3445 of in-plane C=C bonds. Generally, C–F bonds of
cm−1 and peak at 1583.00 cm−1 are assigned fluorinated carbon materials have two natures of
to OH groups and graphite structure present semi ion and covalence. The peak at 1216 cm-1
in the compound. Existence of two peaks at and the shoulder at 1312 cm1 are ascribed to
2923.78 cm-1 and 2851.64 cm-1 showed sp3 the stretching vibration of covalent C–F bonds
C-H bonding which indicated the product

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Advances in Semiconductor Materials and Device Technologies

and C–F2 bonds, respectively. According to SEM images of GO flaky structures are observed
previous studies, covalent and semi-ionic C–F attributed to the formation of layers. All SEM
bonds in F-graphite were distinguished by FT- images shows a dense skin layer and a flaky
IR spectra[6][7]. sub-layer. After being blended with fluorine
functionalization the layers shows structural
c) SEM Analysis: changes. FG shows the formation of layers with
micro sized particles are embedded in layers and
The surface morphology is studied using SEM a more rocky structure is formed.
micrograph (Fig.3). From the cross sectional

Fig. 3. Surface morphology of the graphene derivatives

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Advances in Semiconductor Materials and Device Technologies
IV. Electrical Characterization:
Dielectric measurements are carried out by the impedence analyser and depicted in Fig.4.

Fig. 4. Change of dielectric parameters with frequency

Table 1: Frequency Vs dielectric parameters for FG and GO

Parameter FG GO
Rp( In ohms) Rp: 173832 Rp: 34799
Cp(In Farad) Cp: 1.623 *10-1 Cp: 5.75 *10-1
Dielectric strength (tanδ) Tanδ: 100.92 Tanδ: 153.37
Conductivity(In mho m- ơ max : 0.559*10-4 ơ max: 1.705*10-4

The variation in real part of the dielectric constant values of ε’ at lower frequency. With increase in
(ε’) and tanδ with frequency, for FG and GO frequency, space charge polarization diminishes and
nanostructure is presented in Fig.4. and table 1. For electronic and atomic contribution dominates. This
GO the real dielectric constant has a value of about is also the reason why the dielectric constant attains
153.37 at low frequency and it changed to 100.92 an almost constant value after a certain frequency (as
in the fluoro graphene composite. The conductivity the electronic and atomic contributions become most
is also in the range of semiconductor range, which prominent).
make them suitable for semiconductor applications.
In both the cases, the value of the real dielectric The dielectric loss or ‘tanδ’ represents the energy
constant decreases with increase in frequency and dissipation in the dielectric system. The above graph
become frequency independent at high frequency. shows the variation of tanδ with frequency, at room
Space charge polarization can account for the higher temperature. The graph shows that for both the

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Advances in Semiconductor Materials and Device Technologies

samples, the value of dielectric loss increases with 4. L. Tan, W. Ong, S. Chai and A. Mohamed, “Reduced
frequency at room temperature. From the above graphene oxide-TiO2 nanocomposite as a promising
observations as the functionalization is done the visible-light-active photocatalyst for the conversion of
conductivity decreases and the value is depending carbon dioxide”, Nanoscale Research Letters, vol. 8, no. 1,
on the rate and degree of functionalization. Also p. 465, 2013.
we have observed thatthe conductivity of sample is
in the semiconductor range. These GO and FG can 5. K. Zhang, Y. Zhang and S. Wang, “Enhancing
act as an alternative for silicon capabilities which thermoelectric properties of organic composites through
is most needed. Hence the obtained results of all hierarchical nanostructures”, Scientific Reports, vol. 3, no.
characterizations suggest that the material is useful 1, 2013.
for electrochemical applications.
6. C. Sun, Y. Feng, Y. Li, C. Qin, Q. Zhang and W. Feng,
5. Conclusion “Solvothermally exfoliated fluorographene for high-
performance lithium primary batteries”, Nanoscale, vol. 6,
The functionalized graphene and Graphene Oxide no. 5, pp. 2634-2641, 2014.
(GO) are synthesized the one step hydrothermal
method and modified Hummers Method.The structural 7. W. Feng, P. Long, Y. Feng, and Y. Li, “Two-Dimensional
characterization and chemical composition of samples fluorinated Graphene: Synthesis, structures, properties and
were investigated on the basis of XRD and FTIR applications,” Advanced Science, vol. 3, no. 7, p. 1500413,
spectrum respectively. SEM micrograph represents Mar. 2016
the surface morphology of bot functionalized
graphene. The maximum AC conductivity is 1.704 8. Aziz, M., Abdul Halim, F. and Jaafar, J. (2014). Preparation
* 10-4 andis 0 .5594 * 10-4 for GO FG respectively. and Characterization of Graphene Membrane Electrode
The Fourier transfer infrared spectroscopy (FTIR) Assembly. JurnalTeknologi, 69(9).
analysis confirms the formation of fluorographene.
The peak at 1216 cm-1 and the shoulder at 1312 cm-1 9. Manoratne, C., Rosa, S. and Kottegoda, I. (2017). XRD-
are ascribed to the stretching vibration of covalent HTA, UV Visible, FTIR and SEM Interpretation of
C–F bonds and C–F2 bonds, respectively. The XRD Reduced Graphene Oxide Synthesized from High Purity
analysis shows a shift in 002 peak of 002 plane of Vein Graphite. Material Science Research India, 14(1),
graphite with the incorporation oxygen and fluorine pp.19-30
atom. Hence the present study demonstrates the
change in conductivity value depends upon the 10. W. H. Lee et al., “Selective-area Fluorination of Graphene
functionalization of graphene. The results obtained with fluoropolymer and laser irradiation,” Nano Letters,
from various characterizations suggests that GO and vol. 12, no. 5, pp. 2374–2378, May 2012.
FG can act as an effective semiconductor and whose
electro chemical applications are worth investigating. 11. H. Y. Liu, Z. F. Hou, C. H. Hu, Y. Yang, and Z. Z. Zhu,
“Electronic and magnetic properties of fluorinated
REFERENCES Graphene with different coverage of fluorine,” The Journal
of Physical Chemistry C, vol. 116, no. 34, pp. 18193–
1. S. Peng, X. Fan, S. LI and J. Zhang, “Green synthesis 18201, Aug. 2012.
and characterization of graphite oxide by orthogonal
experiment”, Journal of the Chilean Chemical Society, vol. 12. R. R. Nair et al., “Fluorographene: A Two-Dimensional
58, no. 4, pp. 2213-2217, 2013. counterpart of Teflon,” Small, vol. 6, no. 24, pp. 2877–
2884, Nov. 2010.
2. X. Wang and T. Liu, “Fabrication and Characterization of
Ultrathin Graphene Oxide/Poly(Vinyl Alcohol) Composite 13. J. T. Robinson et al., “Properties of fluorinated Graphene
Films via Layer-by-Layer Assembly”, Journal of films,” Nano Letters, vol. 10, no. 8, pp. 3001–3005, Aug.
Macromolecular Science, Part B, vol. 50, no. 6, pp. 1098- 2010.
1107, 2011.
14. X. Yu et al., “Increased chemical enhancement of Raman
3. P. Cui, J. Lee, E. Hwang and H. Lee, “One-pot reduction spectra for molecules adsorbed on fluorinated reduced
of graphene oxide at subzero temperatures”, Chemical graphene oxide,” Carbon, vol. 50, no. 12, pp. 4512–4517,
Communications, vol. 47, no. 45, p. 12370, 2011. Oct. 2012.

15. K. Samanta et al., “Highly hydrophilic and insulating
fluorinated reduced graphene oxide,” Chemical
Communications, vol. 49, no. 79, p. 8991, 2013.

16. H. Chang et al., “Facile synthesis of Wide-Bandgap
fluorinated Graphene semiconductors,” Chemistry - A
European Journal, vol. 17, no. 32, pp. 8896–8903, Jun.
2011.

17. Mathkar et al., “Synthesis of fluorinated Graphene oxide and
its Amphiphobic properties,” Particle & Particle Systems
Characterization, vol. 30, no. 3, pp. 266–272, Feb. 2013.

18. D. K. Samarakoon, Z. Chen, C. Nicolas, and X.-Q. Wang,
“Structural and electronic properties of Fluorographene,”
Small, vol. 7, no. 7, pp. 965–969, Feb. 2011. 78, no. 8, Aug.
2008.

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Advances in Semiconductor Materials and Device Technologies

19. K. Samanta et al., “Highly hydrophilic and insulating 21. F. Karlický, K. Kumara RamanathaDatta, M. Otyepka,
fluorinated reduced graphene oxide,” Chemical and R. Zbořil, “Halogenated Graphenes: Rapidly growing
Communications, vol. 49, no. 79, p. 8991, 2013. family of Graphene derivatives,” ACS Nano, vol. 7, no. 8,
pp. 6434–6464, Aug. 2013.
20. X. Gao and X. (s. Tang, “Effective reduction of
graphene oxide thin films by a fluorinating agent: 22. R. R. Nair et al., “Spin-half paramagnetism in graphene
Diethylaminosulfurtrifluoride,” Carbon, vol. 76, pp. induced by point defects,” Nature Physics, vol. 8, no. 3, pp.
133–140, Sep. 2014. 199–202, Jan. 2012.

 30

STRUCTURAL, MORPHOLOGICAL AND THERMAL
PROPERTIES OF ZNS: MN DOPED POLYANILINE
NANOCOMPOSITES

Jayasudha Sriram1, Ramya P1, Dr. Priya L2,*, Dr. K.T. Vasudevan3, 1Department of PG Studies

in Physics, CPGS, Jain (Deemed-to-be University), Jayanagar 3rd Block, Bengaluru - 560011. 2Department
of Physics, LRG College for Women, Tirupur, Tamil Nadu 3Department of Physics, Vijaya College, R V Road,
Basavanagudi, Bengaluru-560004. Corresponding e -mail: [email protected]

Abstract position in ZnS lattice. The impurities of manganese
isomorphically replace zinc in the lattice. The degree
In this paper, detailed study of the structural, of homogeneity of Mn2+ions is essential for high
morphological and optical properties of PAni/ efficient luminescence (G. Murugadoss et al., 2009).
ZnS:Mn film were carried out which have been ZnS doped with Mn2+nanomaterials are having high
prepared by a chemical co-precipitation method. quantum efficiency and luminous intensity. Among
Structural and morphological properties have the synthesis techniques chemical co-precipitation is
been studied by X-ray diffraction and Field most popular due to its advantages like it is simple to
Emission scanning electron microscopy. Optical synthesise.
characterization has been done by UV-Vis and
Photoluminescence. In this work, PAni/ZnS:Mn were prepared by a
chemical co-precipitation method. Structural and
Keywords: Field Emission scanning electron microscopy, morphological properties have been studied by X-ray
Conducting polymers, DSC, Pani diffraction and Field Emission scanning electron
microscopy. Optical characterization has been done
1. Introduction by UV-Vis and Photoluminescence.

Conducting polymers and composites are one of the 2. Experimental Technique
major areas of experimental research ever due to
the possibility to control electrical conductivity of Aniline and Ammonium persulphate are prepared
these films from insulating to metallic by doping. in 1:1.2 molar ratios in 3M HCl. Ammonium
A number of metal and metal oxide particles have persulphate solution was added drop by drop to the
been encapsulated into the conductive polymer prepared aniline solution over a period of 30 min with
to form nanocomposites. The incorporation of continuous stirring. A dark green colour was seen
metal nanoparticles acts as a conductive junction indicating the formation of polyaniline. Polymerized
between PAni resulting in an increase electrical sample was purified by dialyzing against distilled
properties of the polyaniline composites. These water and is dried to form films at room temperature.
properties are extremely sensitive to small changes Freshly prepared aqueous solutions of the chemicals
in content, size and shape of the metal nanoparticles were used for the synthesis of nanoparticles.
incorporated. ZnS nanoparticles added with transition These particles were prepared at room temperature
metal ions and rare earth ions have distinct optical by dropping simultaneously 100ml solution of
properties related to traditional bulk materials. These 0.4M of Zinc Sulphate, 100ml of 0.1M solution of
nanocomposites widely used as photoluminescence Manganese Sulphate and 100ml of 0.5M solution
and electroluminescence devices. Luminescence of Sodium Sulphide into 250ml of distilled water
of rare-earth doped systems mainly indicates the containing 100ml of 0.1M solution of EDTA which
features of the dopant. Doped ZnS semiconductor was vigorously stirred using magnetic stirrer. The
materials have extensive range of application in prepared reaction mixture was kept for stirring for
phosphors, light emitting displays, and optical sensors two hours at constant rate of stirring after which the
(WQ Peng et al., 2005). Mn2+ions occupy cation

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mixture was precipitated. The precipitated mixture 4 peaks at 28.51°, 47.6°, 56.3°, 76.76°. Intense
was then separated from the reaction mixture, washed broad peak at 28.51° corresponding to (110)
twice with distilled water to remove the impurities plane of ZnS:Mn indicates the formation of
and the smell. The wet precipitate was dried and nanosturcture (Jyothi P. Borah et al., 2008).
thoroughly grinded. For the preparation of PAni/ XRD pattern also shows three prominent peaks
ZnS:Mn nanocomposite, first ZnS:Mn nanoparticles at 47.8° and 56.3° and 76.76° correspond to
were prepared. The precipitate was washed and dried. (220), (311) and (331) plane of zinc blend
Then PAni was prepared and after 2 hours of stirring, structure. There is an obvious broadening of
ZnS:Mn precipitate was mixed in the PAni solution. the XRD pattern which indicates the formation
It was stirred continuously for 24 hrs. Dialysis was of nano sized ZnS:Mn. The XRD pattern of
carried out for 48 hours against double distilled water nanocomposites shows prominent peak at
and the dialyzed solution was kept for drying. 25.42° for all the concentrations and also both
prominent peak of PAni and ZnS:Mn are seen.
3. Results and Discussion The peak at 28.51° is shifted to lower 2θ value
at 25.42° in nanocomposites. The shift of peak
a) XRD to the lower 2 theta may be due to the variation
of ionic radius of Zn and Mn and Mn2+ ions
Figure 1 illustrate the XRD pattern of PAni, occupying ZnS sites.
ZnS:Mn and PAni/ZnS:Mn of various
concentrations. XRD pattern of ZnS:Mn shows

Fig. 1. XRD of PAni, ZnS:Mn, and its nanocomposites

As the concentration of ZnS:Mn increased in the of the peak confirms the reduction of particle size.
nanocomposites, the peak intensity is found to increase The average particle size of the crystallites of each
till 10%. When the concentration of ZnS:Mn is further sample were determined from the full-width at half
increased the peak intensity got decreased indicating maxima (FWHM) of the XRD peaks by using the
disorganization in the structure. The decrease in Scherrer formula, taking the average of the results
peak intensity can also be attributed to increased from the most prominent peaks. The particle size of
impregnation of new nucleating centres. Broadening ZnS:Mn is found to be ~ 6 nm.

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b) DSC ANALYSIS DSC measures the difference in the heat flow
between the standard reference and the sample
Figure 2 shows the DSC graph of PAni, and to be tested. Thermograph of PAni and its
PAni/ZnS:Mn. The thermal stability is used nanocomposites are recorded from 0°C to 350°C
to analyse the heat stable polymers. Thermal at a rate of 10°C/min. DSC thermogram of PAni
analysis of PAni and its nanocomposites are shows three endothermic peaks.
analysed by Differential Scanning calorimetry.

Fig. 2. DSC graph of PAni and PAni/ ZnS:Mn nanocomposites

An endothermic peak of PAni appears at 50 – 140°C 79°C for 28%). These peaks may be attributed to the
followed by the second peak is in the range between removal for water molecules. The decreased peak
200 – 290°C and another endothermic peak at 292 temperature from 264 °C of PAni to 246, 252, 248,
–311°C. The peak of PAni at 292 °C may occur due 242 and 239 °C in nanocomposites demonstrates
to the degradation of polymeric backbone. ZnS:Mn ordered polymer structure. It also shows that there is
endothermic peaks appears at 150 to 180 °C and a good interfacial interaction between the dopant and
another peak at 242 to 248 °C. PAni/ZnS:Mn shows the polymer matrix.
two peaks. Nanocomposites initial peak is noticed at 3
– 165 °C and the next peak is noticed at 180 – 300°C. REFERENCES
Nanocomposites peak shift to lower temperature
compare to PAni. First endothermic peak shift from 1. Peng WQ et al. (2005) “Concentration effect of Mn2+ on
50 – 3°C and the second peak shift from 200 – 180°C. the photoluminescence of ZnS:Mn nanocrystals” Journal
PAni peak at 108 °C is attributed to the loss of water of Crystal Growth, 279:3-4: 454 – 460.
molecules. In nanocomposites the peak is shifted
to lower temperature except 10% of PAni/ZnS: Mn 2. Murugadoss G. et al. (2009) “Synthesis and
(i.e. 94°C for 1%, 99°C for 3%, 95°C for 5%, and Characterization of Water-soluble ZnS: Mn2+
Nanocrystals”, Chalcogenide Letters, 6:5: 197- 201.

3. Jyothi P. Borah et al., 2008 Borah J P. et al. (2008)
“Structural and optical properties of ZnS nanoparticles”,
Chalcogenide letters, 5:9: 201 – 208.

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NANO CRYSTALLINE CATIO3CERAMIC POWDER
PREPARATION USING MECHANOCHEMICAL METHOD
FOLLOWED BY SUCCESSIVE HEAT TREATMENTS

Almaw Ayele Aniley1*, Naveen Kumar S.K and Akshaya Kumar A
1 Department of Electronics, Mangalore University, Mangalore, India
1*Corresponding author Email:[email protected]
1 Mangalore University, Konaje – 574199, India

Abstract AB2O4 where as that of perovskite types are ABO3.
Where A and B are transitional metals. CaTiO3 is a
The purpose of the study was to prepare perovskite type ceramic material, which is used in
nanocrystalline ceramic CaTiO3 powder using electronics for different applications. Some of the
very simple technique. The technique used was applications are dielectric material and NTC type
manual milling followed by two successive heat thermistor. CaTiO3 ceramic powder can be prepared
treatments. CaTiO3 was prepared 1:1 molar ratio from CaO or CaCO3 and TiO2 oxides by milling using
of CaO and TiO2 powder by manual milling using high energy ball milling or planetary ball milling
stainless steel agate mortar and pestle followed by followed by successive heat treatment[6]. This process
successive heat treatment. The heat treatment was is called mechanochemical or solid state reaction
done with 65oC for two hours and then milling it method of preparing nano ceramic powders, but the
again then finally calcined with 80oC temperature solid state reaction preparation method has its own
for additional two hours. The resulted powder disadvantages. Some of these disadvantages are high
was characterized by FESEM and EDS. FESEM sintering temperature, inhomogeneity, high energy
result showed that the powder was fine in sizeand consumption to mill the powder, and contamination
uniform in morphology. EDS showed that the with impurity. But this method is very a simple
compound contains Ca, Ti and O2. These two one. CaTiO3 can also be prepared from Calcium
characterizing devices confirmed the formation of acetate, calcium nitrate, Titanium isopropoxide
nanocrystalline CaTiO3 ceramic powder. Simple and solvents by using wet chemical method[7].In
milling and successive heat treatment have the this paper synthesis and characterization of CaTiO3
capacity of producing nanomaterial. ceramic powder by using simple manual milling and
successive heat treatment process is presented.
Keywords: CaTiO3, nanoceramic powder, Solid state
reaction, EDS, FESEM 2. Experiment and Methods Used

1. Introduction a) Materials and Equipment Used

Nanomaterials and devices derived from these High purity (99.9%) CaO and TiO2 powders
materials have special physical and chemical purchased from Finar were used. FESEM/EDS
characteristics[1]. These special properties enhances was used to characterize the morphology and
the performance of systems developed from these composition of the sample. Muffle furnace was
devices. Nanoceramic materials are those materials used for successive calcination or heat treatment
derived from metal oxides[2][3], metal acetates[4], and simple homemade agate mortar and pestle
metal nitrates[5], metal carbonates, and metals were also used for milling the mixed powder.
themselves using solid state reaction, sol-gel method
or chemical route method. They have two different b) Methodology
structures. These are spinel structure and perovskite
structures. The general form of spinel structures are Homemade agate mortar and pestle constructed
from stainless steel was used for manual milling.
Muffle furnace was also used for powder

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calcination. Equimolar CaO and TiO2 powders 3. Results and Discussion
were mixed and milled for 30 minutes manually.
The milled powder was calcined at 65oC for 2 The FESEM result confirmed the formation of
hours, then the powder was milled again using perovskite homogeneous nanocrystalline ceramic
the same milling equipment for 30 minutes powder. One can observe from Fig. 1, the formation
manually after that the milled powder was of nanocrystalline CaTiO3 ceramic powder with
calcined at 800oC for 2 more hours. The resulting average particle dimension less than 100nm. The EDS
powder was milled, finally the morphology and result confirmed that the composition of the sample
composition of the powder were characterized were Ca, Ti and O2, but some C atom contaminants
using FESEM/EDS microscopy and spectroscopy are there from the environment after preparing the
devices respectively. powder. The FESEM/EDS results are shown in figure
1 and Fig. 2 respectively.

Fig. 4. FESEM result of nanoceramic CaTiO3 ceramic powder

Fig. 5. EDS results of CaTiO3 ceramic powder

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Advances in Semiconductor Materials and Device Technologies

4. Conclusion Adv. Ceram., vol. 3, no. 2, pp. 117–124, 2014.

Nanocrystalline CaTiO3 ceramic powder could be 3. P. K. Mallik, G. Biswal, S. C. Patnaik, and S. K. Senapati,
easily synthesized using manual milling followed “Characterisation of Sol-Gel Synthesis of Phase Pure
by successive heat treatments. This ceramic powder CaTiO 3 Nano Powders after Drying,” IOP Conf. Ser.
could also be doped with other materials to improve Mater. Sci. Eng., vol. 75, p. 12005, 2015.
its properties. The powder can be used as NTC
thermistor in pellet form, in powder form itself 4. S. Jagtap, S. Rane, S. Gosavi, and D. Amalnerkar, “Low
or thick film form for temperature measurement, temperature synthesis and characterization of NTC powder
regulating electric power, circuit compensation and and its ‘lead free’ thick film thermistors,” Microelectron.
suppression of inrush current. Eng., vol. 87, no. 2, pp. 104–107, 2010.

REFERENCES 5. M. Zhang et al., “Preparation of NiMn2O4 with large
specific surface area from an epoxide- driven sol-gel
1. N. C. Mueller and B. Nowack, “Nanoparticles for process and its capacitance,” Electrochim. Acta, vol. 87,
remediation: Solving big problems with little particles,” pp. 546–553, 2013.
Elements, vol. 6, no. 6, pp. 395–400, 2010.
6. S. Sahoo, U. Dash, S. K. S. Parashar, and S. M. Ali,
2. S. Sahoo, S. K. S. Parashar, and S. M. Ali, “CaTiO3 nano “Frequency and temperature dependent electrical
ceramic for NTCR thermistor based sensor application,” J. characteristics of CaTiO3 nano-ceramic prepared by high-
energy ball milling,” J. Adv. Ceram., vol. 2, no. 3, pp. 291–
300, 2013.

7. Aniley and N. K. S. K, “Soil temperature Sensors in
Agriculture and the role of Nanomaterials in Temperature
Sensors Preparation,” vol. 7, no. 2, pp. 363–372, 2017.

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STRUCTURAL AND OPTICAL PROPERTIES OF ZINC
OXIDE NANOFLOWERS SYNTHESIZED USING
SOL-GEL METHOD

A. Akshaya Kumar*, S.K. Naveen Kumar, Almaw Ayele Aniley
Department of Electronics, Mangalore University, Mangalagangothri, Karnataka, India
*[email protected]

Abstract novel shapes of nanostructures such as nanowires,
nanobelts, nanotubes, nanorings, nanodisks,
Advances in nanoscience and nanotechnology nanoflowers for the different applications [1-2].
make novel shapes of nanoparticles with novel The synthesizing method, bottom-up approach is
physicochemical properties. Different kinds of more advantageous than the top-down approach
metal oxides have been synthesized with small size because the former has a better chance of producing
of <100 nm with shapes resembled to the natural nanostructures with less defects, more homogenous
flowers. In this work, Nanostructured Zinc Oxide chemical composition[3]. Different kinds of metal
(ZnO) Nano flowers were prepared by simple and oxides have been synthesized with small size of
low cost Sol gel method using zinc acetate as the <100 nm with variety of shapes. ZnO is a typical
precursor material. The synthesized ZnO seed II–VI semiconductor of wurtzite structure and has
solution was deposited on the glass substrate by a relatively large direct band gap of 3.3 eV at room
spin coating method. The ZnO seed layer was temperature [4]. Different ZnO nanostructures
annealed at 500 degrees Celsius for two hours have been fabricated by thermal evaporation of
to obtain ZnO Nano flowers. The nanomaterial oxide powders. Recently, chemical solution routes
properties of the ZnO Nano flower thin film including Solvothermal, hydrothermal, self-assembly
were examined with field emission scanning have been employed to synthesize [5]. Sol gel method
electron microscopy (FESEM) with Energy to develop ZnO nanostructures is one of the most
Dispersive Spectrometer (EDS) and the UV visible widely explored methods and good productivity
spectrometer. FESEM showed that uniform and without using any rigorous conditions or sophisticated
well-structured morphology of the nanoflowers. instrumentation [6]. Here work describes the
Energy Dispersive Spectrometer results confirmed Nanostructured Zinc Oxide (ZnO) Nano flowers were
the composition of the nanoflowers which consisted prepared by simple and low cost Sol gel method using
of zinc, oxygen and silicon. UV results confirmed zinc acetate dehydrate as the precursor material. The
the optical characteristics of the material. Zinc nanomaterial properties of the ZnO nanoflowers thin
oxide flowers could be prepared by simple and new film were examined with field emission scanning
sol gel method. The Nano flowers with interesting electron microscopy (FESEM), Energy Dispersive
properties can be used in the design of future Spectrometer (EDS) and the UV visible spectrometer.
devices with various applications.
2. Experiment and Methods used

Keywords: ZnO, Nanoflowers, Spin Coating, Sol gel, a) Materials Used
FESEM, EDS, UV Visible
High purity (99.9%) Zinc acetate
1. Introduction dehydratepurchased from Finar is used as the
precursor material. Ethanol used as the solvent
Advances in nanoscience and nanotechnology material and glass slide as the substrate materials.
investigating new physicochemical properties with

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Advances in Semiconductor Materials and Device Technologies

b) Equipment substrates at 3,000 rpm for 20 s with two step
coating programme. A drying process is then
FESEM, EDS and UV visible spectrometer performed on a muffle furnace at 150°C for
instruments were used to characterize the 10 min. the same coating process repeated
morphology, composition and optical properties three times to obtain thicker and uniform ZnO
of the ZnO thin film material respectively. nanoflowers. The coated nanoflowers layer thin
Spin NXG-P1H model spin coater with films were annealed at 450°C for 2 hours in the
programmable temperature controller used as muffle furnace to remove the unusual elements
the coating equipment and Muffle furnace isused and solvent from the thin films.
for the annealing of the thin film sample.
3. Results and Discussion
c) Methodology
The top-view FESEM images of the ZnO nano
The Glass is used as the substrate material. In flowers that is synthesized with the Glass substrates
the ZnO nanoflowers layer deposition process, are shown in Fig. 1. All of the synthesized ZnO nano
the substrate was cleaned using ultasonicator flowers shows well-structured flower like morphology
with ethanol and acetone. Hot gun from VEGA and also nano flowers are uniformly distributed on
hair blowing to dry the substrate material. the entire surface of the substrate.
After cleaning process spin coater is used to
deposit the ZnO particle solution on the cleaned

Fig. 1. FESEM results of ZnO nano flowers Fig. 2. EDS results of ZnO composition.

Fig. 3. UV Visible spectrometer results of the ZnO solution

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Advances in Semiconductor Materials and Device Technologies

EDS is an analytical technique used for the elemental of the nanoflowers. Energy Dispersive Spectrometer
analysis or chemical characterization of a sample results confirmed the composition of the nanoflowers
shown in Fig. 2. It is confirmed from the EDS analysis which consisted of Zinc, and Oxygen and which
that the grown nanoflowers on glass substrate are confirmed that the grown nanoflowers are pure ZnO.
composed of zinc and oxygen only. Except Zn and UV results confirm the optical properties of the
O, very small peak for carbon and silicon element material.
has been found in the spectrum, these elements occur
from the glass substrate. The weight percentage of REFERENCES
Zinc is 488.70 and Oxygen is 185.77, which again
confirmed that the grown nanoflowers are pure ZnO. 1. Z.S. Hu, J.E. Ramirez, B.E. Cervera, G. Oskam and P.
The UV-visible absorption spectrum of the ZnO C. Searson, J. Phys. Chem. B vol. 109, PP. 11209-11214,
solution is shown in Fig. 3. The absorption spectra 2005.
have a narrow peak near the wavelength of the 300
nanometer. These ZnO nanoflowers with interesting 2. Z.W. Pan, Z.R. Dai ands’. Wang, Science 291, pp. 1947-
structure with optical properties can be used in the 1949, 2001.
design of future devices with various nanomaterial
based applications. 3. Kai Loong Foo, Uda Hashim, Kashif Muhammad and Chun
Hong Voon “Sol–gelsynthesized zinc oxide nanorods and
4. Conclusion their structural and optical investigation for optoelectronic
application” Nanoscale Research Letters 2014.
Simple and new zinc oxide nanoflowers preparation
method is investigated. ZnO nano flowers solution was 4. Ozgur U, Alivov Y I, Liu C, Teke A, Reshchikov M A,
prepared using zinc acetate dehydrate and deposited Dogan S, Avrutin V, Cho S J and Marko H 2005
on the glass substrate by spin coating method. The
properties of the ZnO nanoflowers were examined 5. A comprehensive review of ZnO materials and devices J.
with field emission scanning electron microscopy and Appl. Phys. 98 041301
showed that uniform and well-structured morphology
6. Hui Zhang, Deren Yang1, Xiangyang Ma, Yujie Ji, Jin
Xu and Duanlin Que “Synthesis of flower-like ZnO
nanostructures by an organic-free hydrothermal process”
Nanotechnology 15 (2004) 622–626

7. Jincheng fan, Tengfei, and Hang heng “Hydrothermal
growth of ZnO nanoflowers and their photo catalyst
application” Bull. Mater. Sci., Vol. 39, No. 1, February
2016.

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INFLUENCE RADIATION ON TELLURIUM OXIDE
VARIED SAMARIUM DOPED LANTHANUM-
LEAD- BORATE GLASSES

Madhu.A and B. Eraiah
Department of Physics, Bangalore University, Jnana bharathi campus, Bengaluru-560 056, India
Email: [email protected], [email protected]

Abstract earth ion-doped glasses. Sm3+ doped glasses have been
studied upon subjection of gamma irradiation it has
Samarium doped lanthanum-lead-boro-tellurite proved to be potential candidate for hospital purpose
glasses are prepared by melt quenching method. and dosimetry applications like food irradiation and
Prepared glasses are subjected to gamma accident dosimeter6.
irradiation to study the influence of it. The study
of structure around the rare-earth ion is essential 2. Materials and Methods
to understand the optical properties of rare-earth
ion-doped glasses. Therefore, samples before and Series of glasses TS series: 10La2O3-(20-x) TeO2-
after subjection of radiation is studied in detail. 30PbO-40B2O3-xSm2O3 (where x=0, 0.5, 1,2mol %)
FTIR, Raman and Photoluminescence techniques labelled as TS0, TS05, TS1, TS2 respectively were
were used to study the structural and optical prepared by conventional melt quenching technique.
behaviour of the glasses. Photoluminescence The high purity analytical grade chemicals such as
studies of all samples has revealed that subjection TeO2, H3BO3, PbO, La2O3 and Sm2O3 were used to
of gamma irradiation to all samples of same dose prepare the glasses. In doped samples, the TeO2 was
it retains the luminescence property. Unaltered partially substituted by samarium ions in various
luminescence proves that they exhibit shielding concentrations (x = 0.5, 1, 2 mol %). All the weighed
property which evidences to be potential candidate chemicals (each batch composition of about 10g)
for dosimetry applications. were thoroughly mixed and ground in an agate
mortar to attain homogeneity and transferred to a
Keywords: Melt quenching, Photoluminescence, Raman porcelain crucible, melted in an electrical furnace
spectra, FTIR in the temperature range 900–11800C for 45 min
and quenched at 11800C. The melts were quenched
1. Introduction by pouring it on to a preheated brass moulds. The
glasses were annealed below Tg (3250C) in order to
Recent optical studies by various glass scientists have eliminate the internal stresses. The formed glasses
arrived to the conclusion that heavy metal oxides in were subjected to XRD, FTIR and PL characterization
glasses have potential effects on gamma-radiation before and after irradiation.
causing some shielding behavior because of their
heavy masses and high absorption cross section Fourier Transform Infra-Red spectroscope (FTIR)
for radiation1-4. The spectral absorption curves are measurements were carried out with resolution of 4
observed to remain unchanged or slightly affected cm–1 in the spectral range 400 cm–1 to 4000 cm-1 using
by successive gamma irradiation. Most of the rare Thermo Nicolet, Avatar 370 following KBR pellet
earth ions have an incomplete 4f level, which gives technique. Raman spectroscopy measurements were
rise to the electronically forbidden f–f spectra in the carried out with Ocean optics, MICRO785IDRAMAN
ultraviolet, visible or infrared region. These ions can using 785nm as source. The Photoluminescence
exist in different environments in the glass matrix5. spectrum has been recorded at room temperature by
The study of structure around the rare-earth ion is Spectroflourometer, Horiba Jobin Yvon Fluorolog-
essential to understand the optical properties of rare-

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