Study On P-type Doping And Correlation Problems Of ZnO Films

ZnO is a kind of II-VI compound semiconductor with a wide direct band gap of 3.37 eV that has been widely studied in the recent years due to its great potential for applications. Its high exciton binding energy (60 meV), which is much higher than heat energy (26 meV) at room temperature, will theoretically favor efficient UV excitonic emission processes. In addition, ZnO has a high melting point high thermal and chemical stability. ZnO single crystal thin film can be obtained at the high temperature, so it can greatly reduce the defects formed .furthermore, ZnO is abundant, cheap, innoxious, easy to be prepared and with potential commercial value. These advantages make ZnO a strong candidate for the next generation of ultraviolet light emitting and lasing devices.To realize the application of ZnO in optoelectronic devices, excellent epitaxy n-and thin films are necessary. Based upon that, the ZnO homojunction is fabricated. The formation energy of the intrinsic defects (Zni and Vo) is very low, so there is a heavy compensation in the p-type doping, which makes difficult to chang into p-type ZnO.with the dopant(Al,In,Ge), we have the ability to make high quality n-type ZnO thin films; while the fabrication in a reproducible and stable way of a p-type material, which would satisfy device requirements, remains still a technological challenge. ZnO films have attracted the intense interest for its great potential applications in the optically transparent conducting layers as the electrode for thin-film solar cells. However, the problems such as film uniformity may reduce the transmittance of the visible light. Currently, the crystalloid and transmission of ZnO films has become a hotspot.In this paper, We obtain the C-axis orientation ZnO thin films, choosing single-crystal Si, quartz, K9 and the glass as substrates respectively, by RF magnetron sputtering. With the spectrophotometer, light transmission of ZnO thin films on the transparent substrates is observed, which indicates different oxygen content and substrate may affect the energy band of ZnO thin films. Furthermore, we draw a conclusion that the energy band of ZnO thin films on the quartz substrate is 3.368eV.By nitrogen ion implantance and post-annealing with different time, we have successfully fabricated nitrogen-doped p-type ZnO . Hall-effect measurement on the films gives a hole concentration of 6.62×1016/cm-3.Compared with different annealing tempretures and time, we find the potential hill of ZnO thin films and learn partly doping mechanism and characteristics of p-type ZnO with N, which supply much more references to developments of p-type doping and devices application.