0.25 μm self-aligned AlGaN/GaN high electron mobility transistors

Self-aligned AlGaN/GaN high electron mobility transistors grown on semiinsulating SiC substrates with a 0.25 mu m gate-length were fabricated using a single-step ohmic process. Our recently developed Mo/Al/Mo/Au-based ohmic contact requiring annealing temperatures between 500 degrees C and 600 degrees C was utilized. Ohmic contact resistances between 0.35-0.6 Omega . mm were achieved. These 0.25 mu m gate-length devices exhibited drain current density as high as 1.05 A/mm at a gate bias of 0 V and a drain bias of 10 V. A knee voltage of less than 2 V and a peak extrinsic transconductance (g(m)) of 321 mS/mm, were measured. For their microwave characteristics, a unity gain cutoff frequency (f(T)) Of 82 GHz and maximum frequency of oscillation (f(max)) of 103 GHz were measured.