0.25 µm gate-length, MBE-grown AlGaN/GaNHEMTs with high current and high f T

Abstract
MBE-grown AlGaN/GaN high electron mobility transistors (HEMTs) on sapphire substrates have been fabricated. These 0.25 µm gate-length devices exhibited a maximum drain current density as high as 1.39 A/mm, a unity gain cutoff frequency (fT) of 67 GHz, and a maximum frequency of oscillation (fmax) of 136 GHz. The fT of 67 GHz and fmax of 136 GHz are the highest reported values for 0.25 µm gate-length GaN-based HEMTs.