Effect of substrate temperature on the properties of ZnO thin films prepared by spray pyrolysis

Sprayed ZnO films were grown on glass at different substrate temperatures from 200°C to 500°C and their structural, optical and electrical properties were investigated. All films are polycrystalline with hexagonal wurtzite structure. ZnO films at substrate temperatures above 400°C appear to be better crystalized with (002) plane as preferential orientation. Optical transmission spectrum shows that ZnO films have high transmission (above 80%) in visible region for substrate temperatures above 400°C. Photoluminescence spectra at room temperature show an ultraviolet emission and two visible emissions at 2.82eV and 2.37eV. The resistivity of ZnO films increases with increasing substrate temperatures (above 400°C). The ZnO film deposited at 400°C shows highest figure of merit.