High-$f_{{rm MAX}}$ High Johnson's Figure-of-Merit 0.2- $mu{rm m}$ Gate AlGaN/GaN HEMTs on Silicon Substrate With ${rm AlN}/{rm SiN}_{{rm x}}$ Passivation

摘要

This letter reports a 0.2-$mu{rm m}$ gate AlGaN/GaN high-electron-mobility transistors (HEMTs) on an Si substrate passivated with an ${rm AlN}/{rm SiN}_{{rm x}}$ (4/20 nm) stack layer. The 4-nm-thick AlN was grown by plasma-enhanced atomic-layer-deposition. The ${rm AlN}/{rm SiN}_{{rm x}}$-passivated HEMTs exhibit a high maximum drain current of 930 mA/mm, an three-terminal OFF-state breakdown voltage $({BV}_{{rm DS}})$ of 119 V, and a small threshold voltage shift of 130 mV in a wide drain bias range $(V_{{rm DS}}=3-24~{rm V})$. Owing to the additional positive polarization charge in the AlN passivation layer, the access resistance $R_{s}$ in the GaN-on-Si HEMTs is significantly reduced while maintaining small parasitic gate-drain capacitance $C_{{rm gd}}$, contributing to a high power-gain cutoff frequency $f_{{rm MAX}}$ of 182 GHz and a high Johnson's figure of merit of ${BV}_{{rm DS}}times f_{,T}$ of $6.43times 10^{{12}}~{rm V}/{rm s}$ simultaneously. The accuracy of the RF performance is verified by a small signal modeling based on measured S-parameters.