Growth mechanism of thin film wide-gap semiconductors by chemical bath deposition technique

Abstract

Chemical bath deposition is a thin film technique in which semiconductor thin films of typically 0.02 - 1 mu m thickness are deposited on substrates immersed in dilute baths containing metal ions and a source of sulfide or selenide ions. Many I-VI, II-VI, IV-VI, and V-VI semiconductors are included in the list of materials deposited by this technique, II-VI compounds CdS, CdSe, ZnS and ZnSe being the most investigated. However, a mathematical model describing the growth mechanism of these films still remains to be established. The deposition process consists of a nucleation phase, growth phase, and a terminal phase, each of which depends on the concentration of the ions in the deposition bath, its temperature, dissociation constants of the metal complex ions, etc. In this paper we propose a mathematical model, which can qualitatively account for most of the features of the experimental growth curves of chemically deposited semiconductor films.