Gallium flux induced etching of β-Ga2O3 in an LPCVD system

Gallium flux induced etching, a novel technique to etch β-Ga2O3, is demonstrated and studied in detail in a low pressure chemical vapor deposition (LPCVD) setup. Incoming gallium vapor flux and suboxide reaction rate at the β-Ga2O3 surface are key parameters which affect the β-Ga2O3 etching kinetics. Their influence on the etch rate is systematically studied, demonstrating a controlled etch rate up to ∼0.7 μm/h. To interpret the observed etch rate behavior, a particle conservation based analytical model is adapted and modified to suit the LPCVD configuration. Postetch surface morphology characterization shows vertical sidewalls in samples etched with SiO2 masking while surface roughness of the etched surface is found to improve when etching is performed at higher temperatures. Flexibility to perform in situ etching in LPCVD, which is a low cost epitaxial β-Ga2O3 growth technique, could pave way for economical and improved device fabrication processes such as mesa isolation, gate recess, and contact regrowth.