CVD of Nanosized ZnS and CdS Thin Films from Single-Source Precursors

A chemical vapor deposition (CVD) route to nanosized ZnS and CdS thin films was developed. The layers were deposited on substrates in a atmosphere at temperatures between 473 and 723 K using as single-source precursors. Thermal decomposition and fragmentation of compounds were investigated by thermal analyses and mass spectrometry. The sulfide films were thoroughly characterized in their composition, nanostructure, and morphology by means of several analytical techniques. Surface and in-depth chemical composition was studied by X-ray photoelectron spectroscopy, X-ray excited Auger electron spectroscopy, and secondary ion mass spectrometry. Film nanostructure and surface topography were investigated as a function of the synthesis conditions by glancing incidence X-ray diffraction and atomic force microscopy, respectively. Optical absorption properties were also studied. Nanophasic and contaminant-free ZnS and CdS thin films with an average crystallite size lower than 25 nm were obtained. The layers mainly contained the hexagonal (α) sulfide phase and displayed a smooth and regular surface morphology. In the present work, the influence of synthesis conditions on film characteristics is analyzed and discussed.