Ultra-Wide bandgap Quasi Two-Dimensional β-Ga2O3 with highly In-Plane anisotropy for power electronics

Abstract

β-Ga2O3, as an ultra-wide bandgap semiconductor is a promising material for broad applications for power and deep-ultraviolet (DUV) devices. However, the low-symmetric monoclinic structure resulting the anisotropic characteristic may have a profound impact on device performances. In this work, the anisotropic properties of Raman vibrations, electronic and photoelectric properties for in-plane (100) face of exfoliated quasi two-dimensional (Quasi-2D) β-Ga2O3 have been investigated theoretically and experimentally. It exhibits regularly rectangular-shaped Fast Fourier Transform patterns corresponding to the asymmetric system. Raman scattering intensities of characteristic peaks change periodically with rotated polarization angles. The measured mobility of unintentional doping Quasi-2D Ga2O3 is approximate (mobiltitymax/min = 1.4), which is benefited to fabricate energy-efficient power devices in lower dimension without consideration of the orientation. Whereas, the conductivity and photoresponse of doping Quasi-2D Ga2O3 along c axis are larger than those of b axis, exhibiting a large anisotropic conductance (σmax/min = 5.7) and dichroic DUV responsivity (Rmax/min = 5.1), superior to most 2D anisotropic materials. In addition, calculations based on density functional theory validate a significantly larger electron localization function of O atoms along c axis. And the absorption coefficient is also highly in-plane orientation-dependent. Our work provides a deep insight into Ga2O3 based applications for next-generation high-voltage and anisotropic devices.