Synthesis, microstructure and optical properties of ZnS films formed by electrostatic assisted aerosol jet deposition

ZnS films were synthesised using a novel electrostatic assisted aerosol jet deposition (EAAJD) technique at temperatures above 450 degrees C from an a queous solution of zinc chloride and thiourea. The films showed a mixture o f hexagonal and cubic structures and strong preferred orientations, with th e c-axis normal to film surface. Annealing at higher temperatures improved the crystallinity of the as-deposited films. However, ZnO was formed when t he as-deposited films were annealed in air. The ZnS films exhibit a planar structure with small crystal sizes (< 200 nm). The optical direct bandgap v alues (3.35-3.46 eV) of the as-deposited films were lower than reported val ues for polycrystalline ZnS, probably owing to their poor crystallinity and partial oxidation.