Simulation of a parallel dual-metal-gate structure for AlGaN/GaN high-electron-mobility transistor high-linearity applications

This article proposes a parallel dual-metal-gate structure (PDM) of AlGaN/GaN high-electron-mobility transistors (HEMTs) for high-linearity applications. Cancellation of the third-order derivative of the I${}_{ds}$ - V${}_{gs}$ curve (g${}_m^{\prime \prime }$) is achieved by splitting the device into two subcells in parallel with different gate metals. The two subcells have different threshold voltages. When the same bias voltage V${}_{gs}$ is applied, the operating states of the two subcells are independently controlled by the gate bias voltages. The maximum transconductance (g${}_{m,peak}$) of the conventional single-metal-gate (SMG) HEMT, double-metal-gate (DMG) HEMT, and PDM-HEMT is all comparable, whereas g${}_m^{\prime \prime }$ of the proposed structure is 75% lower than that of the SMG HEMT and 47.8% lower than that of the DMG HEMT. The effects of the differences and width ratios of the work function on g${}_m^{\prime \prime }$ are studied and compared, and a suitably designed PDM-HEMT that can considerably improve linearity without degrading other performance aspects is obtained. This research has significant implications for high-linearity applications. (© 2021 Wiley‐VCH GmbH)