High-quality heteroepitaxial growth of β-Ga2O3 with NiO buffer layer based on Mist-CVD

Abstract

The heteroepitaxial growth of β-Ga₂O₃ on the commonly used sapphire substrate presents great challenges due to their large lattice mismatch. To address this, a NiO buffer layer is proposed to improve the quality of the heteroepitaxial β-Ga₂O₃, as it has a lower lattice mismatch (0.46 %) with β-Ga₂O₃ compared to sapphire (6.6 %). Traditional epitaxial growth methods for Ga₂O₃ are not compatible with NiO growth, so an inexpensive, non-vacuum, and convenient Mist-CVD technology is used for heterogeneous β-Ga₂O₃ growth in this study. XRD and TEM results demonstrate the high quality of β-Ga₂O₃ sample with the clear interface between materials. Introducing a NiO buffer layer enables the Full Width at Half Maximum (FWHM) and root-mean-square (RMS) roughness of β-Ga₂O₃ to reduce from 0.726° to 0.514° and from 7.47 nm to 3.34 nm respectively. Additionally, through the UDM analysis model, micro-strain within the film is found to significantly decrease. This work proposes a novel approach to improve the quality of β-Ga₂O₃ heteroepitaxial growth on sapphire substrate, contributing to the advancement of Ga₂O₃ materials and devices.