Abstract
This letter reports an Al 0.65 Ga 0.35 N-Al 0.4 Ga 0.6 N metal-oxide-semiconductor-heterojunction-field-effect-transistor (MOSHFET) with an SiO 2 gate-insulator. For this first demonstration of an AlGaN channel MOSHFET, a new doped barrier epilayer design led to linear source-drain ohmic-contacts formed by Zr-based metal stack with a contact resistance as low as 1.64~\Omega \cdot \textsf {mm} . For a device with 6- \mu \text{m} source-drain opening a record saturation current of 0.6 A/mm (at gate bias of 6V) was measured. In contrast to a conventional Schottky-gate HFET, the gate-oxide from the pulsed plasma enhanced chemical vapor deposition decreased the MOSHFET gate leakage current by a factor of 10 4 with only a 1.5-V shift in the threshold voltage. A drift mobility of 430 cm ^{2}/\textsf {V}\cdot \textsf {s} is measured at zero-gate bias, which increases to 800 cm ^{2}/\textsf {V}\cdot \textsf {s} close to the threshold voltage. The device characteristics up to 250°C are used to calculate the temperature dependence of the drift mobility.