Single-Crystalline ZnO Films Grown on (0001)Al2O3 Substrate by Electron Cyclotron Resonance-Assisted Molecular Beam Epitaxy Technique

Abstract

High quality epitaxial ZnO films were grown on c-plane sapphire substrates at low temperature using the electron cyclotron resonance-assisted molecular beam epitaxy (ECR-assisted MBE) technique, in which zinc vapor provided by a Knudsen cell reacted with oxygen activated in an ECR source on the surface of sapphire substrate. The crystal structure and the surface morphology of the films were investigated. It was confirmed that the ECR-assisted MBE technique was capable of growing high quality epitaxial ZnO films on c-plane sapphire substrates at low temperatures in comparison with CVD or RF sputtering deposition. Furthermore, the FWHM of an X-ray rocking curve of the (0002) peak for a 0.33 µ m-thick ZnO film grown epitaxially at the substrate temperature of 275° C and the oxygen pressure of 2×10^-4 Torr was as narrow as 0.58°.