Crystallinity and Polarity of Indium Nitride Films Grown on the c-face of Zinc Oxide

Abstract

Indium nitride (InN) films were grown on the c-face of zinc oxide (ZnO) single crystals by molecular beam epitaxy, and their interfacial structure and crystalline polarity were examined. The c-parameter and the crystallinity of the films strongly depended on the substrate polarity and growth temperature. In particular, the low-temperature-grown films on the oxygen terminated c(-)-face of ZnO (c(-)-ZnO) were single crystalline films with a shorter c-axis than that of bulk InN, while the films grown on the zinc terminated c (+) -face of ZnO (c(+)-ZnO) and the high-temperature-grown films had low crystallinity. Coaxial impact-collision ion scattering spectroscopy (CAICISS) revealed that the low-temperature-grown films on c(-)-ZnO had (0001) In-faces, namely c (+) -polarity (c (+) -InN), and TEM observations suggested the existence of an interfacial layer a few atomic thick in the c (+) -InN/c (-) -ZnO heterostructure. These results on the lattice restriction and the polarity of InN films are discussed in terms of the interfacial structure at the InN/ZnO boundary.