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

In this letter, partial recessed-gate AlAl 2 O 3 /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 \text{V}_{\textsf {th}} and lower ON-resistance. As a result, it achieves a positive shift in {V}_{\textsf {th}} as compared to the reference (from 1.8 to 2.5 V). Besides, this method accomplished the highest reported peak \mu _{\textsf {FE}} value of 2033 cm 2 / \textsf {V}\cdot \textsf {s} and a lower gate channel sheet resistance of 519~\Omega /\Box (access region, {R}_{\textsf {sh}} of 418~\Omega /\Box ) 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.