Enhancement-mode Pseudomorphic In0.22Ga0.78As-channel MOSFETs
with InAlP Native Oxide Gate Dielectric
Keywords: Enhancement mode, InGaAs-channel MOSFET, InAlP oxide, RF applications
As an alternative to conventional III-V HEMTs and MESFETs for high-speed and wireless applications, enhancement-mode pseudomorphic In0.22Ga0.78As-channel MOSFETs with an ultra-thin InAlP native oxide gate dielectric are reported. The gate dielectric is formed by wet thermal oxidation of a 2 nm InAlP epitaxial layer, resulting in a 3.5 nm thick InAlP oxide gate dielectric. The gate oxide reduces the gate leakage below that of HFETs based on the same epitaxial structure by more than 105 times. A typical 0.5 μm gate length device exhibits a threshold voltage of 1.05 V, a peak extrinsic transconductance of 146 mS/mm, and a saturation drain current density of 95 mA/mm. A cutoff frequency, fT, of 34 GHz, and a maximum frequency of oscillation, fmax, of 49 GHz have also been achieved. These results suggest that RF applications could benefit from III-V MOSFETs with native oxide gate dielectric.