Inversion-type enhancement-mode HfO2-based GaAs metal-oxide-semiconductor field effect transistors with a thin Ge layer

Using a thin germanium (Ge) interfacial passivation layer (IPL), GaAs HfO2-based inversion-type enhancement-mode metal-oxide-semiconductor field effect transistors (MOSFETs) are realized. The n-channel MOSFETs on semi-insulating GaAs substrate clearly show surface modulation and excellent current control by gate bias. The threshold voltage of ∼0.5V, the transconductance of ∼0.25mS∕mm, the subthreshold swing of ∼130mV/decade, and the drain current of ∼162μA∕mm (normalized to the gate length of 1μm) at Vd=2V and Vg=Vth+2V are obtained. In comparison with previous reports, the dc characteristics of the inversion-type GaAs MOSFETs with a Ge IPL and HfO2 dielectric demonstrate much similar results.