Preparation Of Na-N Codoped P-type ZnO Thin Films By RF Magnetron Sputtering

Zinc oxide (ZnO) is a novelⅡ-Ⅵcompound semiconductor with a wide direct bandgap. It has a very broad application space and development potential in application of optoelectronic, piezoelectric, thermoelectric and ferromagnetic multiple properties, especially in application of optoelectronic due to its direct wide-bandgap (3.37eV) and high exciton binding energy (60meV). ZnO is a new type of short-wavelength light emitting device material, and the key to make use of the ZnO-based optoelectronic devices is to prepare n-type and p-type ZnO films with the excellent properties. At present, we can only obtain the n-type ZnO films with excellent performance. However, p-type ZnO doping has encountered many obstacles which are the bottleneck and also the greatest challenge in the practical application of ZnO. This subject is also the focus on this study, and this paper is based on ZnO p-type doping.1. Prepare the Na-N codoped p-ZnO films in different parameters, and give the detail analysis of Na-N codoped p-ZnO mechanism.Na-N co-doped p-type ZnO [ZnO: (Na, N)] thin films were prepared on glass substrates by RF magnetron sputtering (RFMS) and post-annealing techniques in the N₂O ambient. We changed the prepared parameters such as annealing temperature, gas pressure, etc, in order to find the optimum growth conditions. When the target is 0.5 at% Na₂O-ZnO (99.99%), Ar/N₂O is 30:70, substrate temperature is 500℃, gas pressure is 3Pa, X-ray diffraction (XRD) measurements showed that all films possessed a good crystallinity with c-axis preferential orientation. Hall measurements showed that the electrical properties of ZnO: (Na, N) films were improved after annealing and the p-type behavior was realized. The film annealed at 450℃showed the lowest resistivity of 139.2Ωcm with a Hall mobility of 0.2 cm²/Vs and carrier concentration of 2.5×10¹⁷cm^-3.2. Compare the performance of three kinds of films: ZnO: N, ZnO: Na and ZnO: (Na, N), and give the detail analysis of Na-N codoped mechanism according to the XPS test results.ZnO: N, ZnO: Na thin films were prepared on glass substrates by RFMS and post-annealing techniques in the N₂O ambient as ZnO: (Na, N) films, and we compared the performance of three kinds of films: ZnO: N, ZnO: Na and ZnO: (Na, N). XPS measurements showed that Na_Zn acceptor in ZnO: (Na, N) is responsible for the p-type conductivity of the ZnO: (Na, N). Also, Na-N complex may exist in the films, which act as acceptors. Detailed investigation is now in progress.