AlGaN/GaN-on-Silicon Metal--Oxide--Semiconductor High-Electron-Mobility Transistor with Breakdown Voltage of 800 V and On-State Resistance of 3 m$\Omega$$\cdot$cm2 Using a Complementary Metal--Oxide--Semiconductor Compatible Gold-Free Process

This letter reports the fabrication and characterization of undoped AlGaN/GaN-on-silicon metal--oxide--semiconductor high-electron-mobility transistors (MOS-HEMTs) using a complementary metal--oxide--semiconductor (CMOS) compatible gold-free process. Devices with a gate-to-drain $L_{\text{GD}}$ spacing of 5 μm achieved an off-state breakdown voltage $V_{\text{BR}}$ of 800 V and an on-state resistance $R_{\text{on}}$ of 3 m$\Omega$$\cdot$cm 2 . In addition, subthreshold swing $S$ of ${\sim}97$ mV/decade and $I_{\text{on}}/I_{\text{off}}$ ratio of ${\sim}10^{6}$ were obtained. Compared with those of gold-free GaN MOS-HEMTs having a gate-to-drain spacing $L_{\text{GD}}$ of less than 10 μm, the $V_{\text{BR}}$ achieved in this work is the highest.