Epitaxial Growth of m-Plane ZnO Thin Films on (10(1)over-bar0) Sapphire Substrate by Atomic Layer Deposition with Interrupted Flow

Abstract

Nonpolar ZnO films were grown epitaxially on (10 (1) over bar0) sapphire substrates at 200 degrees C by atomic layer deposition with interrupted flow. The latter method improved the crystalline quality of ZnO films, transformed the structure from polycrystalline to epitaxial, and enhanced the optical properties of near-band-edge emission. The interfacial structure shows multiple domain phases along sapphire (020) and the disappearance of a minor phase near the surface. As determined by X-ray diffraction, the epitaxial relation between ZnO and sapphire follows [002](ZnO)vertical bar vertical bar[020](sapphire) and [020](ZnO)vertical bar vertical bar[006](sapphire). The photoluminescence intensity increased with increasing crystalline quality and thickness of ZnO films.