Influence of Al-Doping on the Optical Properties of ZnO films
S.Y. Ma, H.X. Chen, J.T. Glass, C.B. Parker
Northwest Normal University, CN
Keywords: R.F magnetron sputtering, Al doped ZnO film, luminescence mechanism
Abstract:Al doped ZnO (AZO) thin films were deposited on glass substrates using the radio frequency reactive magnetron sputtering technique. The effect of Al concentration on the microstructure and the luminescence properties of the AZO thin films was studied by X-ray diffraction (XRD) and fluorescence spectrophotometer. The results showed that the crystallization of the films was promoted by appropriate Al concentration; the photoluminescence spectra (PL) of the samples were measured at room temperature. Strong blue peak located at 436nm (2.85eV), weak green peaks located at about 495nm (2.51eV) and 530nm (2.35eV) were observed from the PL spectra of the samples. When the Al concentration is 2％, the intensity of the blue peak increased sharply. It was concluded that the blue peak may correspond to the interstitial zinc and the green emission peaks must be related to the electron transition from the deep oxygen vacancy level to the top of the valance band. In addition, absorption and transmittance properties of the samples were researched by UV spectrophotometer; the variation of the optical band gap was analyzed. Finally, we discuss the luminescence mechanism of the samples.