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An indigenous and simple electronic control system for Langmuir-Blodgett (LB) film deposition set-up has been developed. This set-up consists of a microstepping circuit to drive the stepper motors with precision and smooth motion, essential for controlled movement of the barriers and substrate in the LB set -up. Linear variable differential transformer (LVDT)-based displacement measuring device has been developed and used to measure the surface pressure of the monolayer material spread on the water surface. A control program is written which incorporates all operational modes required to drive the set -up and to acquire the data in situ using a set of user -friendly commands. This control set-up has been successfully used to plot the pressure -area isotherm of various amphiphilic compounds such as ferric stearate, zinc arachidate etc. and for deposition of ordered LB films of ferric stearate.

Large size KDP crystals with a maximum cross-section of 4.5 x 4.5 cm2 were grown by solution growth technique. Good quality tetragonal DKDP crystals of size 7 cm long and 1.5 x 1.5 cm2 cross-section were grown from 99.4% heavy water. Tetragonal crystals were grown from the monoclinic stability region of the solution, after optimising all the growth parameters. Large area SHG cells were fabricated for high power lasers and the conversion efficiency of the cells were found to be comparable with the commercially available cell.

Comparison of the conversion efficiency for efficient second-harmonic generation of Nd: YAG laser radiation is reported for KDP, LAP, KTP, BBO and LBO crystals. Conversion efficiencies as high as 50% and 46% were obtained for our laboratory-grown KDP and LAP crystals respectively, for power densities well below their damage thresholds.

We present experimental evidence for the large Raman and photoluminescence enhancement in CdSe semiconductor films grown on Si and glass substrates due to excitation of surface plasmon resonances in proximate gold metal nanoparticles deposited on the surface of CdSe film. Heterojunction diodes containing n‐CdSe on p‐Si semiconductor were fabricated and the surface of the diodes was in situ coated with Au nanoparticles using the ultra‐high vacuum pulsed‐laser deposition technique. A significant enhancement of the photocurrent was obtained in CdSe/p‐Si containing Au nanoparticles on the surface compared to CdSe/p‐Si due to the enhanced photo‐absorption within the semiconductor by the phenomenon of surface plasmon resonance. These observations suggest a variety of approaches for improving the performance of devices such as photodetectors, photovoltaic, and related devices, including biosensors.

We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Current Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from 1 to 30 V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.

A control system for Langmuir-Blodgett (LB) film set-up has been developed based on the principle of microstepping of the stepper motors to drive the barriers and the substrate with precision and smooth motion. The stepper motors and the Wilhelmy plate used to measure the monolayer surface pressure are interfaced to a microcomputer for automatic operation. This home-made LB film set-up has been successfully used to fabricate LB films of cadmium arachidate of high crystalline quality.