Epitaxial Growth of High Quality Nonpolar InN Films on LiGaO2 Substrates

A new system for obtaining high quality nonpolar InN films has been demonstrated. It is found that a-plane InN epitaxially grows on LiGaO2 (001) with high phase purity and smooth surface. The in-plane epitaxial relationships are InN [0001]// LiGaO2 [100], and InN [1 (1) over bar 00]// LiGaO2 [010]. The interface between the substrate and a-plane InN is atomically abrupt. The threading dislocation density drops dramatically from 2 x 10(10) cm(-2) of its initial growth stage to 3 x 10(9) cm(-2) when the InN film thickness reaches 30 nm, which we believe is driven by dislocation merging or annihilation near the nucleation layer. The band edge emission from its photoluminescence spectra of as-grown a-plane InN is located at 0.72 eV. This novel high quality nonpolar a-plane InN on a LiGaO2 (001) system opens up a new possibility for high-efficiency nonpolar InN devices.