Fluoride-plasma-treated bimodal-gate-oxide ALGaN/GaN MOSHEMT for normally-off operation

High-performance enhancement-mode (E-mode) AlGaN / GaN MOSHEMT has been achieved by CF
4
plasma treatment and bimodal-gate-oxide deposition scheme. ALD-Al
2
O
3
is utilized to prevent deep F
⁻
ion implantation into the 2DEG channel, while sputtered-SiO
2
, is employed to suppress the plasma-induced leakage current and increase the gate swing. Compared with the depletion-mode counterpart, thus-fabricated E-mode MOSHEMT exhibited 2.56 V shift in V
th
, but only 8% degradation in I
max
, demonstrating the promise of the bimodal-gate-oxide scheme for realizing E-mode operation of GaN-based MOSHEMTs.