Micro-crystallographic and optical studies on Cd1-xZnxSe thin films

Chemo-mechanical synthesis of (Cd, Zn)Se thin films with a variable composi tion has been brought about with an objective to study the deposition histo ry and the growth kinetics, structural changes and the optical properties a nd is presented in this paper. The effect of various process parameters (de position time and temperature, concentration of the species, speed of the s ubstrate rotation, pH, etc.) on the growth and quality of the films is stud ied experimentally. At the first insight, mechanistic interpretation of the reaction mechanism is given on the basis of the influence of the process p arameters on the film growth, compositional, structural, microscopic and op tical characteristics of Cd1-xZnxSe thin films. The films are crystalline o ver the whole range studied with a predominant wurtzite structure for 0 les s than or equal to x<0.2 and a zinc blende structure (solid solution) for 0 .7<x less than or equal to 1. The film compositions in the middle of the ra nge (0.2 less than or equal to x<0.7) include both the cubic and the hexago nal structures. The crystal size determined from the XRD and SEM micrograph s, is observed to decrease with increasing x (up to x=0.5). The optical gap estimation showed a non-linear increase in the band gap with increasing Zn content in the film. (C) 2000 Elsevier Science S.A. All rights reserved.