Effects of O2 fraction on the properties of Al-doped ZnO thin films treated by high-energy electron beam irradiation

We demonstrated the effects of O-2 fraction on the properties of high-energy electron beam irradiation (HEEBI) treated Al-doped ZnO (AZO) films prepared by radio frequency magnetron sputtering using various O-2 fraction conditions. Hall and photoluminescence (PL) measurements revealed that for HEEBI-treated AZO films with a dose of 10(16) electrons/cm(2), the p-type conductivity was exhibited for films with O-2 fractions in range of 0.3-0.9 while the n-type conductivity was observed for films with an O-2 fraction of 0. Hall results also indicated that HEEBI-treated AZO films prepared by O-2 fractions of 0.3 and 0.9 can be used for p-channel layers in the applications of transparent thin film transistor. PL and X-ray photoelectron spectroscopy showed that the acceptor-like defects, such as zinc vacancies and oxygen interstitials, increased in the HEEBI-treated films prepared by O-2 fractions in range of 0.3-0.9, resulting in the p-type conductivity in the films. We conclude from the X-ray diffraction analysis that worse crystallinity with a smaller grain size as well as higher compressive stress was observed in the films prepared by a higher O-2 fraction, which is related to incorporation of more oxygen atoms into the films during deposition. The study of atomic force microscope suggested that the roughest surface morphology was observed in HEEBI-treated films prepared by an O-2 fraction of 0.3, which causes the highest resistivity in those films, as evident by Hall study. (C) 2010 Elsevier B.V. All rights reserved.