Annealing effects of sapphire substrate on the structure and properties of ZnO films grown via pulsed laser deposition.

The structure, morphology, and properties of ZnO films were examined in relation to an annealed sapphire substrate prepared via pulsed laser deposition. The annealing effects of the sapphire substrate on the ZnO films were studied via X-ray diffraction (XRD), atomic-force microscopy (AFM), and photoluminescence (PL) measurements. The XRD patterns and PL spectra results showed that the optical quality of the ZnO films was significantly affected by the annealing temperature of the sapphire substrate. The optimum annealing temperature of the sapphire substrate was 1400 C. Atomically-flat-surface and high-density atomic steps were formed after annealing treatment, which were qualified to be good nucleation sites for ZnO film growth.