Experimental determination of the band offsets at the UWBG p-LiGa5O8/Ga2O3 interface

Abstract

LiGa5O8, a recently discovered ultrawide bandgap semiconductor exhibiting p-type conductivity at room temperature, is grown on (010) β-Ga2O3 substrate. Utilizing a mist chemical vapor deposition method, LiGa5O8 thin film grown on insulating Ga2O3 substrate exhibits hole concentration ∼2.31 × 1018 cm−3 and hole mobility ∼2.07 cm2/V s. The resulting heterostructure is characterized comprehensively. A smooth, uniform film growth was observed by scanning electron microscopy and atomic force microscopy imaging. Cross-sectional scanning transmission electron microscopy and x-ray diffraction confirm the growth of spinel cubic crystal structure of LiGa5O8 along the [110] direction. Moreover, the valence and conduction band offsets at p-LiGa5O8/β-Ga2O3 heterointerface were determined via x-ray photoelectron spectroscopy. The determined band alignments at LiGa5O8/β-Ga2O3 interface reveal the formation of a type-II (staggered) heterojunction. The experimental measurements provide valuable parameters of the band offsets at the heterointerface, addressing a crucial aspect for future power electronic device design and fabrication based on β-Ga2O3 ultrawide bandgap semiconductors.