Al2O3/AlN/GaN MOS-Channel-HEMTs With an AlN Interfacial Layer

We report a high-performance normally-off Al₂O₃/AlN/GaN MOS-channel-high electron mobility transistor (MOSC-HEMT) featuring a monocrystalline AlN interfacial layer inserted between the amorphous Al₂O₃ gate dielectric and the GaN channel. The AlN interfacial layer effectively blocks oxygen from the GaN surface and prevents the formation of detrimental Ga-O bonds. Frequency-dispersion in C-V characteristics and threshold voltage hysteresis are effectively suppressed, owing to improved interface quality. The new MOSC-HEMTs exhibit a maximum drain current of 660 mA/mm, a field-effect mobility of 165 cm²/V·s, a high on/off drain current ratio of ~10¹⁰, and low dynamic on-resistance degradation.