Influence of substrate temperature on the structure and optical properties of ZnO thin films grown by pulsed laser deposition

Highly c-axis oriented ZnO thin films were fabricated on Si(111) substrates at different substrate temperatures by pulsed laser deposition X-ray diffraction and atom force microscope were employed to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were investigated by photoluminescence with He-Cd laser and synchrotron radiation as light source. The ZnO thin films grown at 500 degrees C show good crystallinity and intense UV emission. We also observed the violet emission centering about 430nm of ZnO films excited by synchrotron radiation at 18K. The violet luminescence is ascribed to the defects related to the interface traps existing at the grain boundaries, which probably originate from interstitial zinc(Zn-i).