Reduction of MOS interfacial states between β-Ga2O3 and Al2O3 insulator by self-reaction etching with Ga flux

In this Letter, self-reaction etching (SRE) with Ga flux demonstrates the capability of eliminating surface contaminations and damage, as well as improving the electrical characteristics of the interface between monoclinic gallium oxide (beta-Ga2O3) and the insulator. Compared to post-tetramethyl ammonium hydroxide wet chemical treatment, SRE is a low damage repair method that effectively removes surface contaminants introduced during previous inductively coupled plasma etching of beta-Ga2O3 without surface damage. As a consequence, the surface band bending on the beta-Ga2O3 surface decreased as demonstrated by the core-level peak shifts of x-ray photoemission spectroscopy, which indicated fewer negative charges remained on the surface. Furthermore, the interface state density (D-it) between beta-Ga2O3 and an Al2O3 insulator was determined by using high-temperature conductance and photoassisted C-V measurements. The D-it dropped significantly for samples treated by SRE as compared with other treatments. These results suggested that SRE is an attractive etching candidate for future Ga2O3 power device fabrication.