High-voltage accumulation-mode lateral RESURF GaN MOSFETs on SiC substrate

Lateral, accumulation-mode gallium nitride (GaN) MOSFETs were fabricated on a silicon-doped GaN epilayer on a AlGaN isolation layer on a conducting 6H-SiC substrate. The polysilicon gate was formed over a 100 nm silicon dioxide gate dielectric deposited by low-pressure chemical vapor deposition at 900°C. The accumulation-layer field-effect mobility is measured to be 110 cm²/V-s. GaN MOSFETS with a 9 μm RESURF length were characterized with an on-resistance of 140 mΩ-cm² at V_GS=15 Volts and breakdown voltage ≤180 Volts attributed to tunneling through the AlGaN isolation layer.