Heteroepitaxial growth of ZnO films by PLD

Here we present our recent work on the fabrication of high crystalline and optical quality ZnO films on sapphire (001) by pulsed laser deposition. The influence of deposition parameters such as the substrate temperature, oxygen pressure, laser fluence, and pulse repetition rate on the crystalline quality of ZnO layers has been studied. The omega-rocking curve FWHM of the (002) peak for the films grown at 750 degrees C, oxygen pressure 10(-5) Torr was 0.17 degrees. The XRD-phi scans studies revealed that the films were epitaxial with a 30 degrees rotation of the unit cell with respect to the sapphire to achieve a low energy configuration for epitaxial growth. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2-3% in the near surface region (similar to 2000 Angstrom). The atomic force microscopy revealed smooth hexagonal faceting of the films. The optical absorption edge measured by UV-Visible spectroscopy was sharp at 383 nm. Excellent crystalline properties of these epi-ZnO/sapphire heterostructures are thus promising for m-V nitride heteroepitaxy.