Improved dc and power performance of AlGaN/GaN high electron mobility transistors with Sc2O3 gate dielectric or surface passivation

The dc and power characteristics of AlGaN/GaN MOS-HEMTs with Sc2O3 gate dielectrics were compared with that of conventional metal-gate HEMTs fabricated on the same material. The MOS-HEMT shows higher saturated drain–source current (∼0.75 A/mm) and significantly better power-added efficiency (PAE, 27%) relative to the HEMT (∼0.6 A/mm and ∼5%). The Sc2O3 also provides effective surface passivation, with higher drain current, lower leakage currents and higher three-terminal breakdown voltage in passivated devices relative to unpassivated devices. The PAE also increases (from ∼5% to 12%) on the surface passivated HEMTs, showing that Sc2O3 is an attractive option for reducing gate and surface leakage in AlGaN/GaN heterostructure transistors.