High power 0.25 µm gate GaN HEMTs on sapphire with power density 4.2 W/mm at 10 GHz

Metal organic chemical vapour deposition-grown AlGaN/GaN high electron mobility transistors (HEMTs) with power density up to 4.2 W/mm, one of the highest values ever reported for 0.25 µm gate-length AlGaN/GaN HEMTs, were fabricated on sapphire substrates. The devices exhibited maximum drain current density as high as 1370 mA/mm, high transconductance up to 223 mS/mm, short-circuit current gain cutoff frequency (fT) of 67 GHz, and maximum frequency of oscillation (fmax) of 102 GHz.