Reduction in leakage current through interface between Ga2O3 epitaxial layer and substrate by ion implantation doping of compensating impurities

Abstract

Strong accumulation of Si impurities has been observed at a Ga2O3 epilayer/substrate interface. The highly Si-doped region around the interface typically becomes a current conduction path, causing buffer leakage for lateral Ga2O3 field-effect transistors (FETs). To overcome the drawback, we performed Mg- or Fe-ion implantation doping into a Ga2O3 substrate prior to the subsequent molecular-beam epitaxy growth to compensate the accumulated Si donors at the interface. The Mg implantation doping showed a minimal effect on reduction in the interface leakage, irrespective of its concentration. On the other hand, the Fe doping with a high density of 2 × 1019 cm−3 provided a significant decrease in the leakage and decent FET characteristics.