Molecular Beam Epitaxial Growth of Single-Crystalline ZnO Films on a-Plane Sapphire Substrates
Kazuto KOIKE, Tomonori KOMURO, FengPing YAN, Ken-ichi OGATA, Shigehiko SASA, Masataka INOUE and Mitsuaki YANO
Abstract:This paper describes radical-source molecular beam epitaxial growth of ZnO films on a-plane sapphire substrates. Reflection high-energy electron diffraction observation and x-ray diffraction measurement show that single-crystalline ZnO (0001) films without any rotational domains are obtained on the sapphire substrates. Photoluminescence spectra measured at 300 K exhibit an intense emission peak from free excitons. The result of Hall measurement shows that phonon scattering becomes dominant with increasing temperature and a relatively high electron mobility of `100 cm2/Vs with a low residual electron density of `4~1017 cm-3 at 300 K is achieved. Key Words:ZnO film, Sapphire substrate, Single crystal, Radical source molecular beam epitaxy