Effect of the temperature and HCl partial pressure on selective-area gas etching of (001) & beta;-Ga2O3

We investigated the anisotropic selective-area HCl-gas etching behavior of SiO2-masked (001) & beta;-Ga2O3 and its dependence on the temperature T (548 & DEG;C-949 & DEG;C) and HCl partial pressure P (0)(HCl) (25-250 Pa). The cross-sectional width-to-depth aspect ratio of the etched trenches formed under the striped window along [010] decreased with increasing T and decreasing P (0)(HCl). Secondary-ion mass spectrometry revealed slight diffusion of Si into & beta;-Ga2O3 at T = 949 & DEG;C, while no diffusion was detected at T = 750 & DEG;C. These results provide practical guidelines for the fabrication of desired three-dimensional structures, such as fins/trenches, for high-performance & beta;-Ga2O3-based power devices.