Radhakrishnan, M K; Dr.Joy, George(Cochin University of Science And Technology, February , 1981)
[+]
[-]
Abstract:
The Thesis consist of the study of the electrical properties of antimony trisulphide films and the electrical behaviour of different metal contacts to antimony trisulphide films. Since the thermal evapouration of the compound antimony trisulphide as such mayresult in nonstoichiometric compound films , sb2s3 films in the present work were mostly prepared by the three temperature method ,keeping the substrate at different temperature ranging from 3031 to 4231 and evapourating antimony and sulphur simultaneously from separate sources.
Description:
Department of Physics, Cochin University of Science And Technology
Urmila, K. S; Dr. Pradeep, B.(Cochin University of Science and Technology, August 6, 2016)
[+]
[-]
Abstract:
The use of energy in our day to day life has grown exponentially and
conserving energy to meet the world’s escalating energy demands is the need of
the hour. During the past decade there is a heightened awareness all over the
world that the production costs of energy from coal, oil and natural gas is
increasingly higher and at the same time the energy technologies involving their
use are contributing to a serious rise in the greenhouse gases in the environment
and a consequent global warming. As a result, more attention is focused on the
utilization of clean energy technologies, especially solar energy which has a
great potential to meet a large fraction of world’s energy demands using
photovoltaics (PV). The heart of the PV system that efficiently convert sunlight
directly into electricity through photovoltaic effect is the solar cell - originally
developed for space applications in the 1950s, are now used in consumer
products, mounted on roofs of houses or assembled into large power stations.
Sudha Kartha, C; Pramitha, Vayalamkuzhi; Rani, Joseph; Sreekumar, K(Optical Society of America, June 13, 2011)
[+]
[-]
Abstract:
An investigation on the panchromaticity of a silver-doped poly(vinyl alcohol)/acrylamide photopolymer
system is presented in this paper. Frequency-doubled Nd:YAG (532 nm) and Arþ (488 nm) lasers were
used for the characterization of the films. Previous studies using an He–Ne laser (632:8 nm) showed that
plane-wave transmission grating with a high diffraction efficiency of 75% could be stored in the optimized
film. From the present study, it was noted that transmission gratings with 70% diffraction efficiency
could be recorded using Arþ and Nd:YAG lasers, thereby elucidating the possibility of using the developed
photopolymer system as a competent panchromatic recording medium
Joseph, K S; Dr.George, Joy(Cochin University of Science and Technology, 1983)
[+]
[-]
Abstract:
In this thesis the preparation and properties of thin films of certain semiconducting sulphides (sulphides of tin, copper and indium) are reported. As single source evaporation does not yield satisfactory films of these compounds for a variety of reasons, reactive evaporation of the metal in a sulphur atmosphere has been used for film preparation. It was found that for each metal sulphide a stoichimetric interval of fluxes and substrate temperature exists for the formation of the compound in accordance with the analysis of Guenther. The first chapter of the thesis gives a resume of the basic principles of semiconductor physics relevant to the work reported here. In the second chapter is discussed in detail the reactive evaporation techniques like ordinary reactive evaporation, activated reactive evaporation and reactive ion plating. Third chapter deals with the experimental techniques used in this study for film preparation and characterization. In the next seven chapters is discussed the preparation and properties of the compound films studied. The last chapter gives a general theory of the formation of compound films in various deposition techniques in terms of the kinetic energy of the film forming particles. It must be mentioned here that this is of fundamental importance to thin film deposition and is virtually untouched in the literature
Description:
Department of Physics, Cochin University of Science and Technology
Benoy, M D; Dr.Pradeep, B(Cochin University of Science and Technology, May 7, 2001)
[+]
[-]
Abstract:
The investigation of physical properties of matter has progressed so much
during the last hundred years. Today physics is divided in to a large distinct group
of special branches. These branches are distinguished by the particular area
studied, method of investigation and so on. An independent and important branch
that has developed is the physics ofthin films.Any object in solid or liquid form with one of its dimensions very much
smaller than that of the other two may be called a thin film. It is having only one
common property, namely, one of their dimensions is very small, though all their
physical properties may be different. Thin layers of oil, floating on the surface of
water, with their fascinating colours, have attracted men’s curiosity from time
immemorial. The earliest application of thin films was the protective coatings in
the form of paints. A thin layer of tin has been used from ancient times to protect
copper utensils from corrosion. Indium thin films are used in certain applications
on account of their good lubricating property. Relay contacts are coated with thin
films of rare earth metals in order to prevent burning due to arcing. Hard coatings
are also available using diamond like carbon (i-carbon). The basic properties of
thin films are of considerable interest because of their potential applications in
various fields of science and technology
Description:
Department of Physics, Cochin University of Science And
Technology
Binoy, Paul; Dr.Girijavallabhan,C P(Cochin University of Science & Technology, February , 2004)
[+]
[-]
Abstract:
Nonlinear optical processes in organic compounds have attracted considerable interest in the field of science and technology because of their compelling technological promises in fields of optical communication,computing,switching and signal processing.As a result of the synthesis of novel organic compounds with varying degree of nonlinear optical strength, many practical devices based on these are getting realised giving new theoretical insights into the nonolinear optical behaviour of materials.Organic compounds like phthalocyanines and porphyrins have evoked great deal of interest in the field of photonic technology.The present thesis describes the results obtained from the investigations carried out on the nonlinear optical properties of certain organo-metallic compounds using Z-Scan and DFWM techniques.
Description:
International School of Photonics,
Cochin University of Science & Technology
Mridula, S; Dr.Mohanan, P(Cochin University Of Science And Technology, July 7, 2005)
[+]
[-]
Abstract:
The thesis relates to the investigations carried out on Rectangular Dielectric
Resonator Antenna configurations suitable for Mobile Communication applications.
The main objectives of the research are to:
- numerically compute the radiation characteristics of a Rectangular DRA
- identify the resonant modes
- validate the numerically predicted data through simulation and experiment
0 ascertain the influence of the geometrical and material parameters upon the
radiation behaviour of the antenna
° develop compact Rectangular DRA configurations suitable for Mobile
Communication applications
Although approximate methods exist to compute the resonant frequency of
Rectangular DRA’s, no rigorous analysis techniques have been developed so far to
evaluate the resonant modes. In this thesis a 3D-FDTD (Finite Difference Time
Domain) Modeller is developed using MATLAB® for the numerical computation of the radiation characteristics of the Rectangular DRA. The F DTD method is a
powerful yet simple algorithm that involves the discretimtion and solution of the
derivative form of Maxwell’s curl equations in the time domain.
Description:
Department of Electronics, Cochin University of Science and
Technology
Deepti Das, Krishna; Dr.Aanandan, C K(Cochin University of Science and Technology, September , 2010)
[+]
[-]
Abstract:
In recent years, there is a visible trend for products/services which demand
seamless integration of cellular networks, WLANs and WPANs. This is a
strong indication for the inclusion of high speed short range wireless technology
in future applications. In this context UWB radio has a significant role
to play as an extension/complement to existing cellular/access technology.
In the present work, we have investigated two major types of wide band
planar antennas: Monopole and Slot. Four novel compact broadband antennas,
suitable for poratble applications, are designed and characterized, namely
1. Elliptical monopole
2. Inverted cone monopole
3. Koch fractal slot
4. Wide band slot
The performance of these designs have been studied using standard simulation
tools used in industry/academia and they have been experimentally verified.
Antenna design guidelines are also deduced by accounting the resonances in
each structure.
In addition to having compact sized, high efficiency and broad bandwidth
antennas, one of the major criterion in the design of impulse-UWB systems
have been the transmission of narrow band pulses with minimum distortion.
The key challenge is not only to design a broad band antenna with constant
and stable gain but to maintain a flat group delay or linear phase response
in the frequency domain or excellent transient response in time domain. One
of the major contributions of the thesis lies in the analysis of the frequency
and time-domain response of the designed UWB antennas to confirm their
suitability for portable pulsed-UWB systems. Techniques to avoid narrowband
interference by engraving narrow slot resonators on the antenna is also
proposed and their effect on a nano-second pulse have been investigated.
Description:
Department of Electronics,
Faculty of Technology,
Cochin University of Science and Technology
Suma,M N; Dr.Mohanan, P(Cochin University of Science & Technology, January , 2008)
[+]
[-]
Abstract:
The space constraints on wireless gadgets is a challenge to antenna designers as the ground plane dimensions of the printed monopole significantly affect s the antenna characteristics.Investigations on ground plane truncations have led to the development of an extremely broad band printed monopole antenna.Omnidirectional radiation characteristics with moderate gain makes this antenna highly suitable for mobile/wireless applications .This thesis also highlights the development of UWB printed antenna along with design equations .Optimum ground plane dimensions for compact antenna applications,folding technique for miniaturization and double folding for dual band application are the other highlights of this thesis.
Description:
Department of Electronics,
Cochin University of Science and Technology