Suppression of Gate Leakage and Enhancement of Breakdown Voltage Using Thermally Oxidized Al Layer as Gate Dielectric for AlGaN/GaN Metal–Oxide–Semiconductor High-Electron-Mobility Transistors

Abstract
A synthetic route for alumina based dielectric layer for AlGaN/GaN metal–oxide–semiconductor high-electron-mobility transistors (MOS-HEMT) has been developed. The approach is based on oxidative annealing of thin Al layer deposited prior to Schottky gate metallization. The MOS-HEMT exhibits good pinch off features withIdsmaxandgmmaxof 421 mA/mm and 121 mS/mm, respectively. Frequency dependent conductance measurements yielded a minimum trap density (DT) and trap transient time (TT) of 2.2 ×1012cm-2eV-1and 1.3 µs, respectively. The oxide layer suppresses the gate leakage by two orders of magnitude and enhances the breakdown voltage (BV) of the devices. A highBVof 431 V and figure of merit (FOM) of 1.89 ×108V2Ω-1cm-2for 15 µm device at (Lgd≤4 µm) was observed for Al2O3based MOS-HEMT.

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