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

Abstract

Using a thin germanium (Ge) interfacial passivation layer (IPL), GaAs $\mathrm{Hf}{\mathrm{O}}_2$ -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 $\sim 0.5\mathrm{V}$ , the transconductance of $\sim 0.25\mathrm{mS}∕\mathrm{mm}$ , the subthreshold swing of $\sim 130\mathrm{mV}$ /decade, and the drain current of $\sim 162\mu \mathrm{A}∕\mathrm{mm}$ (normalized to the gate length of $1\mu \mathrm{m}$ ) at $V_d=2\mathrm{V}$ and $V_g=V_{\mathrm{th}}+2\mathrm{V}$ are obtained. In comparison with previous reports, the dc characteristics of the inversion-type GaAs MOSFETs with a Ge IPL and $\mathrm{Hf}{\mathrm{O}}_2$ dielectric demonstrate much similar results.