A robust GaN p-FET with unconventional electron conduction

GaN p-channel field-effect transistors (p-FETs) are critical for enabling complementary integration of power and logic, while offering high breakdown capability. However, achieving high on-current in GaN p-FETs remains a significant challenge, primarily due to the low hole concentration, poor mobility, and challenges in forming stable, low-resistance ohmic contacts. Here, we present a novel GaN p-FET architecture that exhibits unconventional electron conduction, which helps enhance both thermal response and current modulation. We conduct a comprehensive investigation of heavily Mg-doped p⁺⁺-GaN layers, focusing on contact optimization for high-temperature operation. Structural and interfacial characterization confirms high crystal quality and a thermally robust Ni/Au contact stack stabilized by an interfacial Ni_xO_y layer. This strategic interfacial layer, combined with moderate-temperature annealing, promotes Mg activation and suppresses oxygen-related traps, resulting in a ~ 73% reduction in contact resistance. Temperature-dependent analysis further reveals non-monotonic Schottky barrier modulation driven by interface evolution. Integrated into the device, this contact strategy enables thermally enhanced operation, with a drastically increase in on-state current and threshold voltage shifting positively by ~ 69% with temperature. These findings highlight a model shift in GaN p-FET design, where interface study and transport-mode innovation enable high-performance, thermally resilient devices for next-generation power integration.