Side-gate effects on the direct current and radio frequency characteristics of AlGaN/GaN high-electron-mobility transistor on Si

Abstract

The influence of the side-gate bias on the direct current and radio frequency characteristics for a GaN high electron mobility transistor is studied. When the side-gate is biased at large negative bias (VSG = −100 V), the maximum drain current density (Idmax), maximum extrinsic transconductance (gmmax), cut-off frequency (fT), and maximum oscillation frequency (fmax) of the device are reduced and the threshold voltage (Vth) is positively shifted. The drain leakage current under pinch-off is decreased. In contrast, when VSG is positive, there are only small changes for the fT, fmax, Idmax, gmmax, and Vth. The drain leakage current under pinch-off condition is increased at VSG = +100 V. It is believed that the electrical field effect and buffer depletion caused by the additional side gate voltage contribute to those changes.