Growth and optical absorption spectra of ZnO films grown by pulsed laser deposition

ZnO films on Al2O3 substrate were grown by using a pulsed laser deposition method. Through photoluminescence (PL) and X-ray diffraction (XRD) measurements, the optimum growth conditions for the ZnO growth were calculated. The results of the XRD measurement indicate that ZnO film was strongly oriented to the c-axis of hexagonal structure and epitaxially crystallized under constraints created by the substrate. The full-width half-maximum for a theta curve of the (0 0 0 2) peak was 0.201°. Also, from the PL measurement, the grown ZnO film was observed to be a free exciton, which indicates a high quality of epilayer. The Hall mobility and carrier density of the ZnO film at 293 K were estimated to be 299 cm2/V sec and 8.27×1016cm-3, respectively. The absorption spectra revealed that the temperature dependence of the optical band gap on the ZnO films was Eg(T)=3.4393eV − (5.30×10-4eV/KT2/(367+T).