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 (β-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 β-Ga2O3 without surface damage. As a consequence, the surface band bending on the β-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 (Dit) between β-Ga2O3 and an Al2O3 insulator was determined by using high-temperature conductance and photoassisted C–V measurements. The Dit 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.