Aluminum-nitride codoped zinc oxide films prepared using a radio-frequency magnetron cosputtering system

Al-N codoped zinc oxide films were prepared using a radio-frequency magnetron cosputtering system at room temperature. AlN and ZnO materials were employed as the cosputtered targets. The as-deposited cosputtered films at various theoretical atomic ratios [Al/(Al+Zn) at. %] showed n-type conductive behavior in spite of the N atoms exceeding that of the Al dopants, indicating that the N-related acceptors were still inactive. The crystalline structure was obviously correlated with the cosputtered AlN contents,and eventually evolved into an amorphous structure for the Al-N codoped ZnO film at a theoretical Al doping level reaching 60%. With an adequate postannealing treatment, the N-related acceptors were effectively activated and the p-type ZnO conductive behavior achieved. The appearance of the Zn3N2 phase in the x-ray diffraction pattern of the annealed Al-N codoped ZnO film provided evidence of the nitrification of zinc ions. The redshift of the shallow level transition and the apparent suppression of the oxygen-related deep level emission investigated from the photoluminescence spectrum measured at room temperature were concluded to be influenced by the activated N-related acceptors. In addition, the activation of the N acceptors denoted as N-Zn bond and the chemical bond related to the Zn3N2 crystalline structure were also observed from the associated x-ray photoelectron spectroscopy spectra. (c) 2007 American Institute of Physics.