Fabrication And Properties Of ZnO Thin Films

Recently, thin films prepare technique has developed fast because of the development of materials sciences in micro-electronics field and it is important in advanced technique and new materials field. Investigated of preparation technique of thin film is very important because of its variety applications in electronics and instrument filed. One important advantage of ZnO is that it is a II–VI semiconductor of wurtzite structure with a wide direct-band-gap of 3.3 eV at room temperature. The most unique property of ZnO is its large exciton binding energy of 60 meV, which is much larger than those of GaN (28meV), ZnSe (20meV) and ZnS (39meV). Because of this large binding energy, the exciton is stable at room temperature even in bulk crystals. Owing to these properties, ZnO is considered as a promising material for light-emitting devices and semiconductor lasers with low thresholds in the UV region, such as light-emitting diodes and laser diodes. ZnO films with high intensity emission have been deposited by using several growth techniques, such as metal-organic chemical vapour deposition (MOCVD), molecular beam epitaxy (MBE), sol–gel deposition, rf magnetron sputtering and reactive DC sputtering, oxidation of metal zinc film, pulse laser deposition (PLD). Pulsed laser deposition (PLD) technique is more useful in obtaining high quality thin films of metal oxide materials compared with other techniques, because of its advantage of simple hardware, atomic-layer control obtained by adjusting the laser energy density, the pulse duration and repetition rate. For these practical reasons, PLD technique has been wildly applied for the formation of the high quality thin films. In our article, we adopted the method of ZnO thin films deposited on Si(111)at different substrate temperature by laser (wavelength of 1064 nm) ablation of Zn target in oxygen active atmosphere. The influence of substrate temperature and oxygen pressure on the surface morphology and photoluminescence property was studied. In PLD, in general the excimer lasers have been widely used to grow ZnO thin films because of its shorter wavelength and small pulse duration, and high...