High performance 0.25 μm gate-length AlGaN/GaN HEMTs on sapphire with transconductance of over 400 mS/mm

Metal organic chemical vapour deposition-grown AlGaN/GaN high electron mobility transistors (HEMTs) having record high transconductance of over 400 mS/mm have been fabricated on sapphire substrates. These 0.25 µm gate-length devices exhibited maximum drain current density as high as 1.4 A/mm, unity gain cutoff frequency ( fT) of 85 GHz, and maximum frequency of oscillation ( fmax) of 151 GHz. The fT of 85 GHz and fmax of 151 GHz are the highest ever reported values for 0.25 µm gate-length GaN-based HEMTs.