Atomic layer deposition of ZnS via in situ production of H2S

Atomic layer deposition (ALD) of ZnS films utilizing diethylzinc and in situ generated H2S was performed over a temperature range of 60 degrees C-400 degrees C. This method for generating H2S in situ was developed to eliminate the need to store high pressure H2S gas. The H2S precursor was generated by heating thioacetamide to 150 degrees C in an inert atmosphere, producing acetonitrile and H2S as confirmed with mass spectroscopy. ALD behavior was confirmed by investigation of growth behavior and saturation curves. The properties of the films were studied with X-ray diffraction, transmission electron microscopy, ellipsometry, atomic force microscopy, scanning electron microscopy, ultraviolet visible spectroscopy, and X-ray photoelectron spectroscopy. The results show a growth rate that monotonically decreases with temperature, and films that are stoichiometric in Zn and S. The root mean square roughness of the films increases with temperature above 100 degrees C. A change in crystal phase begins at 300 degrees C. The band gap is dependent on the crystal phase and is estimated to be 3.6-4 eV. (C) 2010 Elsevier B.V. All rights reserved.