Improved Gate Stability of Metal–Insulator–Semiconductor-High-Electron-Mobility Transistors with 10 nm Atomic Layer Deposition Al2O3 by Tetramethylammonium Hydroxide Wet Treatment

We investigated the impact of predeposition surface treatment with a tetramethylammonium hydroxide (TMAH) solution on the performance of recessed gate metal–insulator–semiconductor-high-electron-mobility transistors (MIS-HEMTs). When applying the forward step stress, gate leakage current of the TMAH-treated device becomes 1 order of magnitude smaller. Step stress tests carried out at various voltages showed a stable threshold voltage with both the reverse gate bias step stress and the off-state drain step stress contributing to the high-quality Al2O3/AlGaN interfaces. When the temperature was increased to 473 K, the maximum field effective mobility (μFE) was improved from 450 to 483 cm2/V·s, and on-resistance was improved by ∼6.8%.