Enhancement-Mode Pseudomorphic $hbox{In}_{0.22} hbox{Ga}_{0.78}hbox{As}$-Channel MOSFETs With Ultrathin InAlP Native Oxide Gate Dielectric and a Cutoff Frequency of 60 GHz

摘要

Enhancement-mode pseudomorphic $hbox{In}_{0.22}hbox{Ga}_{0.78}hbox{As}$ -channel MOSFETs with an ultrathin native InAlP oxide gate dielectric are demonstrated. The gate dielectric, a 3.5-nm-thick oxide grown by wet thermal oxidation from epitaxial InAlP, reduces the gate leakage below that of HFETs based on the same epitaxial structure by more than $hbox{10}^{5}$ times. The devices operate in enhancement mode, with 0.25-$mu hbox{m}$ gate length devices exhibiting a measured threshold voltage of 0.25 V, a peak intrinsic transconductance of 245 mS/mm, and a saturation drain current density of 165 mA/mm. A record-high current gain cutoff frequency $f_{rm T}$ of 60 GHz has also been achieved. These results indicate the applicability of InAlP oxide-based InGaAs-channel MOSFETs for use in single power supply RF applications.