Low Leakage Current and High-Cutoff Frequency AlGaN/GaN MOSHEMT Using Submicrometer-Footprint Thermal Oxidized ${rm TiO}_{2}$/NiO as Gate Dielectric

摘要

AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMTs) with thick $({>}{rm 35}~{rm nm})$, high-$kappa~({rm TiO}_{{2}}/{rm NiO})$ , submicrometer-footprint (0.4 $mu{rm m}$) gate dielectric are found to exhibit two orders of magnitude in lower gate leakage current ( ${sim}{rm 1}~{rm nA}/{rm mm}$ up to ${+}{rm 3}hbox{-}{rm V}$ applied gate bias), higher $I_{rm{MAX}}$ (709 mA/mm), and higher drain breakdown voltage, compared to Schottky barrier (SB) HEMTs of the same geometry. The maximum extrinsic transconductance of both the MOSHEMTs and the SBHEMTs with $2times80hbox{-}mu{rm m}$ gate fingers is measured to be 149 mS/mm. The addition of the submicrometer-footprint gate oxide layer only results in a small reduction of the current gain cutoff frequency (21 versus 25 GHz, derived from $S$-parameter test data) because of the high permittivity $(kappaapprox 100)$ of the gate dielectric. This high-performance submicrometer-footprint MOSHEMT is highly promising for microwave power amplifier applications in communication and radar systems.