ZnO : Zn phosphor thin films prepared by ion beam sputtering

ZnO:Zn phosphor thin films used in field emission displays were prepared by ion beam sputtering. Postdeposition annealing of these films was performed at temperatures ranged from 100-1000 degrees C in N-2 atmosphere. Several techniques, including Rutherford backscattering spectroscopy (RBS), x-ray d iffraction, atomic force microscopy, Hall effect measurement, and photolumi nescence spectra, were employed to characterize these films. RES results sh owed there was an amount of excess Zn in the films. The as-deposited films were found to contain both amorphous and crystalline phases. The morphology of the films consisted of several structures. It was detected that the fre e carrier concentration of these films decreased by increasing annealing te mperature, indicating the elimination of excess Zn. Meanwhile, the Hall mob ility increased quickly if the annealing temperature exceeded 400 degrees C , showing the improved crystallinity. Two categories of photoluminescent pe aks, ultraviolet/violet and blue/green, were detected in ZnO:Zn films. The singly ionized oxygen vacancies were responsible for the visible luminescen ce which was strongly affected by the annealing processes. The possible rea sons may include recovery of structural defects, homogenization of the film s, and evaporation of the excess Zn with different contributions at differe nt temperature ranges. (C) 2000 American Vacuum Society. [S0734-2101(00)084 05-0].