GaN MOS-HEMT Using Ultra-Thin Al₂O₃ Dielectric Grown by Atomic Layer Deposition

We report a GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) with atomic layer deposited (ALD) Al₂O₃ gate dielectric. Based on the previous work Appl. Phys. Lett. 86 (2005) 063501 of Ye et al. by decreasing the thickness of the gate oxide to 3.5nm and optimizing the device
fabrication process, the device with maximum transconductance of 150mS/mm is produced and discussed in comparison with the result of 100mS/mm of Ye et al. The corresponding drain current density in the 0.8-μm-gate-length MOS-HEMT is 800mA/mm at the gate bias of 3.0V. The gate leakage is two orders of magnitude lower than that of the conventional AlGaN/GaN HEMT.
The excellent characteristics of this novel MOS-HEMT device structure with ALD Al₂O₃ gate dielectric are presented.