High-Mobility Normally OFF Al₂O₃/AlGaN/GaN MISFET With Damage-Free Recessed-Gate Structure

In this letter, partial recessed-gate Al2O3/AlGaN/GaN MISFET is experimentally demonstrated based on selective-area growth. The device features different contents of Al in the AlGaN barriers that were grown in the recessed and accessed regions that contributed to a higher Vthand lower ON-resistance. As a result, it achieves a positive shift in Vthas compared to the reference (from 1.8 to 2.5 V). Besides, this method accomplished the highest reported peak μFEvalue of 2033 cm2/V · s and a lower gate channel sheet resistance of 519 Ω/□ (access region, Rshof 418 Ω/□) owing to reserving damage-free AlGaN/GaN hetero-structure in the recessed-gate. Notably, the formed device also exhibits a low hysteresis, low gate leakage, and a slight current collapse.