| Zinc Oxide (ZnO) is a semiconductor with direct band-gap and has a hexagonal wurtzite structure.The main purpose of this paper is to study the Al doped ZnO thin films, that is, ZAO thin film. ZAO is comparable with the more commonly used indium tin oxide (ITO) films regarding to their electrical and optical properties. Moreover, the film is chemical stable in the presence of active hydrogen or hydrogen plasma atmosphere and will not reduce the activity of solar cell materials because its composition is hard to interact with hydrogen at high temperatures. It is emerging as one of the best alternative candidates for ITO films, and its use will promote the development of cheap transparent conducting films.Al doped ZnO films were deposited by radio frequency (RF) magnetron sputtering technique. X-ray diffraction (XRD), SEM, Ultraviolet-visible spectrophotometer and four-point probe were employed to characterize and analyze the ZAO films.The study shows that:1. Studying the influence of the ratio of O2/Ar to the optical properties of the ZAO thin films (when the films were prepared by the target of pure metal Zn and Al). The need of oxygen was increasing coupled with the tempreture becoming higher.The reason maybe as follows: It needs more oxygen atoms when the reaction became more complete with the higher tempreture; More oxygens cause the higher transmittance and lower resistance.2. Studying the affect of Al-doped and tempreture to the structure,photoelectronic properties The absorption edge shifted to the shorter wave due to the doping of Al; The amount of doped Al affect structure and resistance strongly but little influence to transmittance; The tempreture of substrate have no apparent influence to the properties of the films.3. ZAO/Ti/ZAO films were prepared and compared with the ZAO films .The Ti sandwitch layer made the ZAO/Ti/ZAO films more conductive due to the diffusion. The best resistivity is 1.20×10-2?·cm,the average transmittance is nearly 90%.
|
PDF Full Text Request