D. K. Gautam

Growth and Characterization of Sio 2 Films Deposited by Flame Hydrolysis Deposition System for Photonic Device Application

There are various techniques for the deposition of SiO2 films on silicon. Flame Hydrolysis Deposition (FHD) techniques is the most economical technique for the deposition of SiO2 films. In this technique the SiO2 films are deposited by hydrolysis of SiCl4 in a high temperature H2-O2 flame. In the present study we present the growth of SiO2 films by indigenously developed FHD system and organic compound Tetraethoxyorthosiliate/Tetraethoxysilane TEOS as source of silicon. The films deposited by the FHD system are porous and need annealing at higher temperatures for the densification. We present here for the first time direct dense glassy transparent SiO2 films deposited by our FHD system. The optical properties of the deposited films were studied by ellipsometery. FTIR spectroscopy was carried out to study the various characteristic peaks of SiO2 bonds. The peaks corresponding to Si-O-Si stretching, bending and rocking modes are observed at 1090 cm −1 , 812 cm −1 and 463 cm −1 respectively. The absence of peaks corresponding to the OH bond in the deposited film reveals that the deposited films are most suitable for the photonic devices application. The surface analysis was carried out using SEM. The EDAX of the deposited film confirms the composition of the Si and O in the deposited film.

Growth and Characterization of SiO2 Films for the Fabrication of Optical Waveguides

The SiO2 films grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) system are used for the fabrication of optical waveguides due to their several advantages such as low temperature deposition, controlled refractive index and low tensile stress. These films are preferably used as core and cladding layers in the waveguide. The waveguides formed by the films with controlled refractive index are found to be most suitable for the coupling with the optical fibers as the R.I. are in the range of 1.45 to 1.47. It has been found from the observations that the SiO2 film grown at 300° C shows the excellent properties i.e. better thickness, precisely controlled refractive index and comparatively low tensile stress. The present paper reports the study of the deposition of SiO2 films with indigenously developed PECVD system and their characterization.

Modeling and Simulation of GaN/AlGaN Laser and Temperature Dependent Analysis of Physical Parameters

The computer aided simulation tools have been developed using static device modeling approach for the analysis and optimisation of various physical parameters of the semiconductor lasers.The optical field distribution in various layers across the device is obtained by solving the wave equation. The modal analysis of optical confinement in three layer slab waveguide structure is carried out to obtain the optimized set of structural parameters for maximum intensity at 375 nm wavelength. The basic electrical equations have been implemented in discretized form and solved numerically to obtain the electrostatic potential and quasi Fermi potential at various nodes across the finite difference mesh of the device structure. The self consistent solution of basic electrical and optical equations has been obtained by iterative solution procedure. Recombination rates which have dependency on carrier concentration and recombination coefficient have been determined using various models at individual mesh points of the device. Temperature dependent analysis of recombination coefficient, band gap, refractive index, threshold current density, near field intensity, mirror loss in cavity, effective index has been carried out to explore applicability of nitride lasers at higher temperatures.