AlGaN/GaN Metal–Oxide–Semiconductor High-Electron Mobility Transistors Using Oxide Insulator Grown by Photoelectrochemical Oxidation Method

摘要

A photoelectrochemical oxidation method was used to directly grow oxide layer on AlGaN surface. The annealed oxide layer exhibited $beta$– $hbox{Ga}_{2}hbox{O}_{3}$ and $alpha$ –$hbox{Al}_{2}hbox{O}_{3}$ crystalline phases. Using a photoassisted capacitance–voltage method, a low average interface-state density of $hbox{5.1} times hbox{10}^{11} hbox{cm}^{-2}cdothbox{eV}^{-1}$ was estimated. The directly grown oxide layer was used as gate insulator for AlGaN/GaN MOS high-electron mobility transistors (MOS-HEMTs). The threshold voltage of MOS-HEMT devices is $-$5 V. The gate leakage currents are 50 and 2 pA at forward gate bias of $V_{rm GS} = hbox{10} hbox{V}$ and reverse gate bias of $V_{rm GS} = -hbox{10} hbox{V}$, respectively. The maximum value of $g_{m}$ is 50 mS/mm of $V_{rm GS}$ biased at $-$2.09 V.