Determination of the band offsets of the Ga2O3:Si/FTO heterojunction for current spreading applications

Because of the relatively low electron mobility of Ga2O3, it is important to identify suitable current spreading materials. Fluorine-doped SnO2 (FTO) offers superior properties to those of indium tin oxide (ITO), including higher thermal stability, a larger bandgap, and lower cost. However, the Ga2O3:Si/FTO heterojunction, including the important band offsets and the I-V characteristics, have not previously been reported. In this work, we have grown a Ga2O3:Si/FTO heterojunction and performed x-ray photoelectron spectroscopy measurements. The conduction and valence band offsets were determined to be 0.11 and 0.42 eV, indicating a minor barrier for electron transport and a type-I heterojunction. The subsequent I-V measurement of the Ga2O3:Si/FTO heterojunction exhibited pseudo-ohmic behavior. The results of this work support the potential of FTO for the current spreading layers of Ga2O3 devices for high temperature and ultraviolet applications.