Effects of temperature on properties of ZnS thin films deposited by pulsed laser deposition

The II-VI semiconductors are well-known materials applied as a window layer for thin film solar cells, but the fabrication details still require significant improvement. Compared with CdS, ZnS is eco-friendly and has a wider bandgap, which makes it a promising window layer candidate. In this work, ZnS thin films were deposited at different substrate temperatures with the same thickness on SnO2: F coated glasses by pulsed laser deposition. The structural, morphological and optical properties of ZnS films were studied. The results show ZnS thin films have a face-centered cubic phase. At 350 degrees C, ZnS has the highest degree of crystallinity and roughest surface. Grain size increases from 24 nm to 39 nm and the optical bandgap increases from 3.38 eV to 3.63 eV when temperature rises from RT to 450 degrees C. The ratio of sulfur to zinc atoms is about 1.04-1.07, close to the stoichiometry of ZnS.