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Department of Physics

Jiwaji University, Gwalior was established in 1965 & the School of Studies in Physics was established in 1971, Since then, more than 100 research papers have been published in reputed International & National journals. In recent years most of the research in the department has been confined to theoretical physics owing to the lack of major experimental facilities. This has been aggravated by the exorbitant cost of research instruments and the meager funds made available to the department. We propose to reverse this trend and shift some of the emphasis back to experimental research.

Some of the experimental fields in which the department is engaged are: Thin film semiconductors for solar cells, detectors, sensors, Plasma assisted growth of conducting polymer films, Growth of alkali halides mixed crystals for laser window applications, Study of dislocation and micro hardness of crystals, Transparent conducting oxides, Growth and Crystallographic studies of Fungicides.

Some of the theoretical fields which the department engaged in, are: High - Tc Superconductors, Reformulation of Classical Electrodynamics, High Pressure Physics, Plasma Physics, Neural Network, Non linear optics, Solid State Devices, Particle Physics, Nuclear Physics, Thermo electric power, TCR & size effects of thin films, Molecular dynamics, Computational Physics, Wavelet transform.

The following are the research plans of the department for the next five years:


Development of conducting organic polymer films

We have received a project from DST regarding the preparation of conducting plasma polymerized polymer films. In this we have fabricated conducting, insulating and semi conducting organic polymer films. The films are than characterized for dielectric Breakdown. It was observed that the films were stable upto250V.

Structural studies using XRD data of the poly acetylene shows a polycrystalline films.

Optical properties of poly acetylene revels that these films are having fragmented ring

Structure, and are working as a Ultra violet filter

The department has developed facilities for the preparation of polymer films. These films can be used for the industrial and scientific applications. These films can be used for the protective layers. The opto-electronic properties will guide us for making light emitting diode. The semi conducting polymer will also be used for optical sensors.

Thin film compound semiconductors

Compound semiconductor like CuInSe2 and CdTe are presently being grown in the lab, by chemical method like electrodeposition. CuInS2 and CdS are being grown by chemical spray pyrolysis. CdS is also being grown by the electro less technique.

We have fabricated CdS / CuInS2 solar cells having conversion efficiency close to 5 % and efforts are on to improve the efficiencies as well as to increase the size of the junctions. So far the highest efficiencies have been obtained by us with junction of area ~ 0.03 cm.2 . Our future plan is to electro synthesize and study varies alloys and superstructures involving compounds like CuInSe2 , CuInSSe, CdTeSe, Cd1-xZnxTe and Cd1-xHgxTe in order to tailor their optical and structural properties to suit the requirements of various devices. Modulated structures like super lattices have become extremely important for their improved transport properties and for the novel and interesting physics involved in these systems.

CuInSe2 & CuInS2 have direct band gaps of 1.02 & 1.5 eV respectively and the alloy CuInSe2-xSx can be formed in the entire range of composition. Thus the band gap can be tailored right from 1 eV to 1.5 eV which can be used to improve the conversion efficiencies of CdS / CuInX2 have been separately obtained by this technique. The group II - VI compound semiconductors like CdTe and other important opto electronic materials, alloys like Hg1-xCdxTe are extremely important in IR detectors, but have also been used in solar cells of type Cd1-xHgxTe with reported efficiencies as high as 11 %1. Alloys like Hg1-xCdxTe, Zn1-xCdxTe can be easily grown over a wide composition. in order to engineer the properties the semiconductors. For example Hg1-xCdxTe has a very small band gap (~0.1 eV) when value of x is large (~0.9) and will thus be useful for IR detectors . On the other hand, when x is close to 0.1 the band gap is about 1.3 eV and is highly suitable as a photovoltaic material in combination with a window material like CdS. We intend to study the synthesis of alloys like Hg1-xCdxTe and Zn1-xCdxTe over a wide compositional range by electrodeposition. Electrodeposition has the advantages of simple and low cost instrumentation good reproducibility, high efficiencies of material utilization, inherent purification so that high purity material are not required, high growth rate and uniform deposition over large substrates.

The compounds grown will be characterized by X-ray diffraction, optical transmission and reflection spectra, compositional technique like EDAX, ESCA, AES, AES/SIMS depth profile and electron diffraction.

The alloys will be used to fabricate heterojunctions solar cell of the type CdS/Hg1-xCdxTe . the feasibility of using electrodeposited Hg1-xCdxTe as IR detectors will be studied.

In addition,, electrodeposited super lattices of the form CdTe -ZnTe and CdSe -ZnSe will be fabricated using pulse potential deposition. K. Rajeshwar et. al.2 have successfully demonstrated the use of electrodeposition for the fabrication of such superstructures.

The super lattices will be characterized by XPS-SIMS depth profile, by STM/AFM micrographs by current voltage characteristics and by optical transmission. The periods of the modulated structures will be varied and the effect of changing the period on the current voltage Characteristics will be observed. The experimental results will be compared with results based on theoretical models and calculations. The feasibility of fabricating true nanostructures using electrodeposition will also be studied.

Crystal growth

Alkali halide crystals find their use as laser window materials. They are completely transparent at about 10.2 micron. The main disadvantage in their use as window material arises due to their poor mechanical strength. Hence attempts have been made to improve their mechanical strength without disturbing their optical properties. In this direction the method of solid solution of alkali halide has shown encouraging results. Moreover, the doping by divalent impurities to these solid solution has been found to further increase their strength. Various disputing explanations were given by various workers in the past. It is therefore, plan to grow and characterize the alkali halide solid solutions after doping them with anions of higher ionic radii than that of crystal. The complete plan can be divided in following phases:

  • To grow crystals of alkali halide solid solutions using Czchrolski method and Bridgemann method.
  • To study defect morphology in as grown crystal using etching method.
  • To study micro hardness on Vicker's and knonp scale.
  • To study their TL response behavior on irradiating with high-energy radiation.
  • To study their optical absorption before and after coloration.
  • To study the extent of plastic flow in these crystals.

In order to make possible the above-mentioned study following instruments would be needed in future.

  • Czchralski crystal growing system.
  • Conical crucible for growing crystals.

High - Tc Superconductivity

The challenges and opportunities offered by High Temperature superconductivity are really vital because of their scientific importance as well as technological value. The future for this field seems to be bright. Some of the important objective of research and development programs for next five years in superconductivity in present context are listed here:

  • To develop suitable models to understand the basic mechanism responsible for High Temperature superconductivity and related aspect of these materials. The well - known BCS model with phonon mediated electron pairing does not seem to describe the new oxide superconductors. Although there has been a spate of theoretical papers on high - temperature superconductivity of oxide materials, there is yet no model, which is completely satisfactory. It is necessary to have models, which interpret known results and also make predictions that can be verified experimentally.
  • To acquire better and additional experimental data on the existing high - Tc materials in order to improve our understanding of the essential properties. This is important since only measurements made on pure, homogeneous materials are of real significance. This is especially true of measurements made on relatively large single crystals.
  • To look for new materials (with or without copper ) exhibiting high - Tc. C60 compounds with alkalis have already started a new family of unusual superconductors.
    It is essential that the search for newer materials with high Tc continue. One hope is that someday one will find a material with Tc close to room temperature. Another important effort should be to look for non copper materials with high Tc. If we can discover them, the situation with theory may change dramatically since most of them require the d - orbitals of Cu.
  • Make the efforts to give an idea to the experimentalist regarding the fabrication of materials with the suitable environment for High - Tc in ceramic oxides.

Biophysics

With the rapid development of scientific and industrial growth of manpower and in view of accumulation of information technology, interdisciplinary activities in the field of higher education and research is the demand of the time. With the amalgamation of the computers, Biosciences in general and Biophysics in particular is going to play a crucial role in the 21st century. It is with this view that Medical Council of India has made it mandatory for every medical college to have a department of Biophysics. This will not only be helpful to use the instrumentation and methodology of physical sciences, particularly of Physics, in the service of mankind through medical science but also be imperative to learn more deeply how the laws of physics has to be modified in order to incorporate the basic ingredient of biological sciences, like the concept of Gene, origin of life etc. Thus therefore art of study pertaining to biosciences in general and Biophysics in particular has lot of job potentiality for young and enterprising persons ready to take the challenges of future. Such type of academic activity will also be helpful to develop interdepartmental activities. This point was also emphasized by the UGC in 9th plan proposal. This department is proposing to start M.SC. Biophysics in from July 2002.