Enhancement-Mode AlN/GaN HEMTs With High Ion/Ioff and Low-Leakage-Current Fabricated With Low-Power Surface Oxidation Treatment

Low leakage current enhancement-mode (E-mode) AlN/GaN high-electron mobility transistors (HEMTs) have been successfully fabricated using lowpower surface oxidation treatment (LP-SOT). The oxidation treatment resulted in a reduction of channel electron gas and gate leakage current. The AlN/GaN HEMTs and MOSHEMTs all exhibit a low leakage current, large I
_on
/I
_off
, low subthreshold swing (SS), and low interface states. The record positive threshold voltage (V
_th
) of 0.2 V, considerably large maximum drain current of 1.36 A/mm, low off-current of 2.6 × 10
^-7
A/mm, large I
_on
/I
_off
of 4 × 10
⁶
, and low SS of 70 mV/dec were achieved for E-mode AlN/GaN HEMTs. The high maximum drain current and positive V
_th
were attributed to large sheet electron density difference of samples with LP-SOT before and after deposition of an Al
₂
O
₃
dielectric layer.