Normally Off Single-Nanoribbon $\hbox {Al}_{2} \hbox {O}_{3}\hbox {/GaN}$ MISFET

A single-nanoribbon Al₂O₃/GaN metal-insulator-semiconductor field-effect transistor (MISFET) has been fabricated. The fabricated device exhibits normally off operation with a threshold voltage of 2.1 V. The device also exhibits superior performances such as a maximum drain current density of 1.51 A/mm, a maximum transconductance of 580 mS/mm, and a field-effect mobility of 293 cm²·V^-1·s^-1. This is because the electron concentration in the GaN channels can be increased due to the enhanced gate controllability, which, thus, effectively screens the field lines from the interface traps or the defects near the channels to improve the electron mobility in the channel. The nanoribbon Al₂O₃/GaN MISFET is a very promising candidate for high-performance normally off GaN FETs.