SPECTROSCOPIC ELLIPSOMETRY INVESTIGATION OF PURE, AND Al-DOPED ZnO THIN FILMS DEPOSITED BY RADIO FREQUENCY MAGNETRON SPUTTERING

摘要

Pure ZnO and Al-doped ZnO (AZO) films were prepared on glass substrates at different substrate temperature by RF magnetron sputtering. The micrographs, crystal structures and optical properties of these thin films were analyzed by using SEM images, XRD pattern, and ellipsometry spectra ranging from 400 to 1600 nm. The refractive indices n and the extinctive coefficients k of the films are extracted from the simple Cauchy-Urbach model. Normal dispersion behavior of refractive indices is shown for all samples. For the pure ZnO film, the values of n and k are in the range of ～1.3-2.2 and ～1.7%-15%, respectively. However, the values of n for the AZO films ate in the range of ～1.5-1.8, and that of k in the range of ～0.9%-3.6%. These polycrystalline AZO films deposited at higher temperature can be used in the application of transparent conductive oxide films, as well as solar cell windows.