Effects of substrate temperature on structural and optical properties of S-doped ZnO films

S-doped ZnO films were fabricated on sapphire (0001) substrates by pulsed-laser deposition at different substrate temperatures. Effects of the substrate temperature on the structural and optical characteristic of S-ZnO films were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectrophotometer and fluorescence spectrometer. The results show that the S-doped ZnO thin films are wurtzite crystal structure. And the crystalline quality of S-doped ZnO films improves with increasing the substrate temperature from 400°C to 500°C. And the S/O ration is slowly decreased with substrate temperature elevation attributed to instability of S under the higher deposition temperature conditions. The absorption edges of S-doped ZnO thin films slightly shift blue as the substrate temperature increase from 400°C to 600°C. The photoluminescence (PL) spectra indicates that the visible emissions of S-doped ZnO films are enhanced, as well as the UV emission is weakened comparing to the pure ZnO thin film. It is illuminated that S-doping of ZnO can modify the optical properties of ZnO, which is promising for optoelectronic applications that work in the visible emission region.