Preparation And Characterization Of Phosphorus Doped Zno Films By Magnetron Sputtering

Zinc oxide is a wide band gap (3.37eV) semiconductor with a large exciton binding energy (60meV) and possesses strong exciton emission ability at room temperature. Zinc oxide is considered as an ideal material for UV light-emitting and diodes, widely utilized in piezoelectric parts, ultraviolet light detectors, gas sensors, and other aspects. Therefore, ZnO become a hot topic following the GaN in the wide band gap semiconductor field.In this thesis, preparation of ZnO films and their doping into p-type with phosphorous were investigated. Phosphorus doped ZnO films were prepared on silicon substrate by magnetron sputtering by using high purity Ar and O₂ as the working gas and ZnO: P₂O₅(2wt%) as the target. The crystal quality, electrical and photoluminescence properties of phosphorus-doped ZnO films were improved by post-heat treatment. The phosphorus doped p-type ZnO films were successfully obtained by rapid annealing the phosphorus-doped ZnO films (RTA) at 750℃in air. The effects of annealing temperature and O₂/Ar ratio on structure and electrical and photoluminescence properties of phosphorus doped ZnO thin film were investigated and discussed in detail. This paper also studied the effects of annealing on the intrinsic ZnO films and compared the difference between the intrinsic ZnO and phosphorus doped zinc oxide in structure and properties. The formation mechanism of phosphorus (P) doped p-type zinc oxide was discussed according to the obtained and reported data.Thin films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Hall measurements. The electronic and luminescence properties were tested by photoluminescence (PL).Phosphorous-doped p-type ZnO films can be obtained by rapid annealing at 750 oC in air because the P dopants can be sufficiently preserved in the films and effectively activated. The optimal photoluminescence property was observed for the films deposited at the Ar/O₂ ratio of 1/0.05 and the near-band edge emission diminishes gradually with further increasing the Ar/O₂ ratio. With increasing annealing temperature the crystallinity and photoluminescence property improves and the optimal ones were obtained at 900 oC.