Gallium oxide (Ga2 O3) on gallium arsenide—A low defect, high-K system for future devices

Test devices have been fabricated on a specially grown GaAs/AlGaAs wafer with a 10 nm Ga2 O3 gate dielectric. The wafer has two GaAs transport channels either side of an AlGaAs barrier containing a δ-doping layer. Gate leakage measurements with different gate metals show that transport is by a single activated channel and is dependent on the gate metal work function. C–V studies show that there is little pinning at the oxide–semiconductor interface and confirm the threshold voltage dependence on the gate metal work function. Lateral transport studies are able to distinguish the contribution of the two channels, and there is some indication of reduction of mobility in the channel nearest the oxide. We conclude that, although the oxide is of high quality, the leakage current activation energies are too low for low power device applications without an additional large band-gap oxide also being present.