Study Of Structure And Properties Of ZnO Thin Films Prepared By Ultrasonic Spray Pyrolysis Method

ZnO is a II-VI semiconductor material with wide band-gap, widely used in many areas. Traditionally, ZnO thin films were applied in wave device, gas sensor, transparent electrodes, and so on. Recently, ZnO has .gained more, and more attention in the optoelectronic field of UV detector, Light display etc. Compared to GaN (25emV), high-quality ZnO with a higher binding energy of 60 meV can be synthesized at much lower temperature, which promises strong photoluminescence from bound excitonic emission at room temperature. Up to now, the visible emission and ultraviolet lasing emission of ZnO have been the subject of much research.In this paper, the various growth techniques, applications, and the uptodate progresses in the research of ZnO are reviewed. C-axis oriented polycrystalline ZnO thin films were prepared by self-made Ultrasonic Spray Pyrolysis deposition technique. The structure and properties of the films were characterized by XRD, SEM, AFM, UV-Vis Absorption and PL, etc. The effects of growth parameters on the quality of ZnO films are discussed, such as solution concentration, substrate temperature, deposition time, annealing temperature and doping concentration. As the results shown, heavy solution concentration and low doping concentration are advantageous to grow C-axis oriented ZnO thin films; high oriented ZnO thin films have been deposited at 400 C , and the crystalline of films become better annealed at 600 C in oxygen ambient. The PL spectra of the ZnO thin films show that the strongest UV PL at 390 nm is observed at annealing temperature of 600 C in oxygen ambient, while the visible PL is barely observed, furthermore, it is indicated the instinct and defect PL of ZnO thin films change obviously in different annealing ambient, and in the discussion of visible PL mechanism, we put forward that blue-green PL is caused by the oxygen vacancy or the interstitial zinc defects.