Performance-enhanced NiO/β-Ga2O3 heterojunction diodes fabricated on an etched β-Ga2O3 surface

In this study, performance-enhanced NiO/β-Ga2O3 heterojunction diodes (HJDs) were realized on an etched β-Ga2O3 surface through applying a surface preparation process involving a BCl3/Cl2-based inductively coupled plasma (ICP) etch followed by a hot tetramethylammonium hydroxide (TMAH) treatment. Atomic force microscopy scan and X-ray photoelectron spectroscopy analysis revealed that the ICP etch process created a rough β-Ga2O3 surface with high density small peaks associated with Boron-related etch by-product, which resulted in a dramatic decrease of the HJDs’ breakdown voltage from 1.43 kV to 0.92 kV in average. On the other hand, the TMAH treatment effectively removed the etch-induced damages and contaminations from the β-Ga2O3 surface, therefore obviating its surface instability issue. Consequently, on the processed β-Ga2O3 surface high-quality NiO/β-Ga2O3 heterojunctions with a fully recovered breakdown voltage and an improved turn-on property were successfully formed.