Single-Source CVD of zinc sulfide-based thin films from zinc bis(O-ethylxanthate)

A novel single-source precursor, zinc bis(O-ethylxanthate), was employed for the Chemical Vapor Deposition (CVD) of ZnS-based thin films. The coatings were deposited on SiO2 and SiO2/Si(100) substrates in N2 atmosphere in a cold wall reactor in the temperature range 250-400°C. The film optical properties were investigated by UV-Vis absorption and FT-IR spectroscopies. Their surface and in-depth chemical composition was studied by X-ray photoelectron (XPS), X-ray excited Auger electron (XE-AES) spectroscopies and SIMS (Secondary Ion Mass Spectrometry). Finally, Atomic Force Microscopy (AFM) was employed to analyze the surface morphology of the coatings. Very thin films with thickness less than 30 nm and no evidence of crystalline phases were grown at temperatures of at least 300° C. Optical measurement showed that the coatings were highly transparent (>80%) throughout the Vis and IR spectral ranges.