Microstructure and photoluminescence properties of ZnO thin films grown by PLD on Si(1 1 1) substrates

ZnO thin films on Si(1 1 1) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere; Nd-YAG laser with wavelength of 1064 nm was used as laser source. X-ray diffraction and atom-force microscopy were applied to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were characterized by photoluminescence with an Ar ion laser as a light source. It was found that ZnO film with a majority of c-axis growth grains can be obtained under the condition of substrate temperature 450∼550 °C. Corresponding to the c-axis growth structure, intense UV emission with narrow FWHM was obtained from the ZnO films grown at substrate temperature 500 °C. The green deep level PL emission centering about 518 nm can be attributed to the electron transitions from the bottom of the conduction band to the antisite oxygen O Zn defect levels.