Electrical conductance at Ga2O3/Si interfaces fabricated via surface activated bonding

Abstract

Under ultrahigh vacuum conditions, β-Ga2O3 and Si surfaces form atomic bonds after surface sputtering treatment. It enables the formation of a β-Ga2O3/Si heterostructure, which can contribute to future high-power devices integrated with conventional systems. However, the surface sputtering step generates crystalline damage, hindering electrical conductance across materials. In this study, sputtering conditions were optimized to maximize electrical conductance, and the effects of annealing were investigated to initiate recrystallization. The current between substrates was maximized when Si was sputtered for 40 s and β-Ga2O3 was not sputtered. In addition, annealing at 500 °C achieved ohmic-like current–voltage characteristics between n-type β-Ga2O3 and n-type Si substrates because of recrystallization. An electrically conductive interface can contribute to heterodevices combining β-Ga2O3 devices, which have difficulty in p-type doping, with other materials.