Fabrication and Characterization of CdS Thin Films: Study of the adhesion of II-VI compound semiconductors for applications to light emitting and absorbing devices

Abstract

The structural and optoelectronic properties of polycrystalline CdS films, fabricated by three different methods, are compared to one another for the purpose of preparing CdTe/CdS solar cells. The three methods were: alternated spraying of cation and anion solution at room temperature, spray pyrolysis, and chemical bath deposition. We studied the surface morphology and crystal quality and texture by scanning electron and optical microscopy and x-ray diffraction. All films had a well-developed wurtzite structure. Films grown by the alternated-spray method and the chemical bath method consist of randomly-oriented crystallites with dimensions <0.5 microns. Annealing at 400°C increases the crystallite size slightly. Films which were grown by pyrolysis at substrate temperatures from 400°C to 500°C were oriented in the <002> direction. For growth by pyrolysis at 500°C, the surface is rough on a lateral scale of 0.1 to 0.3 microns.