Preparation Of P-type ZnO Thin Films By Magnetron Sputtering And Investigation On Its Photoelectric Properties

Zinc oxide(ZnO)is a kind of wide band gap semiconductor,which has good electromechanical coupling performance and high exciton binding energy.In addition,its raw materials are accessible,low cost and non-toxic.Owing to these excellent performances,ZnO is widely used in many fields,for example the pressure-sensitive and gas-sensitive elements,piezoelectric devices,solar cell,thin film transparent diodes,laser diode(LD),ultraviolet photodetector,light-emitting diode(LED),etc.At present,ZnO has become semiconductor materials in producing room temperature ultraviolet laser and short wavelength photoelectric device.In the application field of photoelectric materials,the reproducible growth technique of high quality p-type ZnO thin film becomes the main bottleneck and the key problem.In this study,according to the existing problems of preparation technology of p-type ZnO,the magnetron sputtering method was employed,nitrogen(N2)serves as N doping source,Al-N co-doped ZnO thin films were prepared by controlling the parameter of doping concentration,sputtering power,annealing atmosphere and annealing temperature.The optical and electrical properties of the samples were measured by ultraviolet visible spectrophotometer and hall effect measurement system(HEMS),the atomic force microscope(AFM)and x-ray diffraction(XRD)were used to analyse the influence on optical and electrical properties of the samples by the surface topography and surface chemical composition.Some of results are as follows:Radio frequency magnetron sputtering method was used to prepared the N-doped Al:ZnO transparent conductive film with the 99.99%zinc oxide ceramic target(the content of Al is 0.15%)and N2 doping source.The average visible light transmittance of the prepared thin film is above 85%.The p-type N-doped Al:ZnO thin film was prepared with the annealing temperature of 400? and 450? for 15 minutes under the vacuum atmosphere.The N-doped Al:ZnO thin films prepared by the different sputtering power under different nitrogen atmosphere and vacuum annealing conditions,have a hexagonal wurtzite structure characteristics.The crystallinity of the film is the better with sputtering power increases,when the power is too low or too high the film's crystal defect increases.The results show that c axis preferred orientation of the thin film is the best when the sputtering power is 140 w.The p-type N-doped Al:ZnO thin film was prepared by the sputtering power of 140 w and 180 w under the nitrogen atmosphere.And the p-type N-doped Al:ZnO thin film was also prepared by the sputtering power of 140 w under the vacuum atmosphere.When the ratio of nitrogen and oxygen is 9:1,the p-type N-doped Al:ZnO thin films were prepared under the different annealing situation.And the properties of the thin films prepared under the nitrogen annealing atmosphere are more excellent.According to our experiments,the optimal technological parameters for the preparation of the p-type of ZnO thin film are as follow:ratio of o nitrogen and oxygen 9:1,sputtering power 140 w,annealing temperature 400 ?,and annealing time 15 minutes under the nitrogen atmosphere.