Electrical and Optical Properties of Zinc Oxide Thin Films and Heavily Aluminum-doped Zinc Oxide Thin Films Prepared by Molecular Beam Epitaxy

Abstract

ABSTRACTZnO (ZO) and Aluminum (Al) doped ZnO (AZO) films were grown on sapphire substrate via oxygen radical assisted molecular beam epitaxy (MBE) technique. The results of XRD measurement and temperature dependent Hall measurement confirmed that the AZO films were typically highly degenerate semiconductor with good crystallinity. The resistivity of these films were closed to the theoretical lower limit. The optical properties of these films were investigated by photoluminescence (PL) spectra and absorption spectra. Strong band-edge emission was observed in the AZO films with good crystallinity in spite of high carrier concentration more than 1020 cm-3. A sift of absorption edge to higher energy side and a gradual increase of the absorption was observed for the AZO film.