Strained AlInN/GaN HEMTs on SiC With 2.1-A/mm Output Current and 104-GHz Cutoff Frequency

We report on a dc/RF performance of lattice-strained AlInN/GaN high-electron mobility transistors (HEMTs) on SiC substrate. HEMT devices were fabricated with gate periphery of 2 × 150 μm with an 80-nm T-gate and ~2.5-μm source-drain spacing. Fabricated devices simultaneously demonstrated up to 2.11 A/mm with ft-ext = 104 GHz and ft-int = 113 GHz. The high performance is attributed to the combination of low Rsh ~ 230 Ω/sq (μ ~ 1079 cm2/V · s, ns ~ 2.39 × 1013 cm-2) and thin ~110-Å total barrier thickness with a short gate length. Other device parameters include Rc = 0.29 Ω · mm, Ig,leak = 27.9 μA/mm, gm,peak = 432 mS/mm, and Vth = -5.8 V. To our knowledge, this is among the highest current densities reported for any HEMT operating with a unity current gain frequency exceeding 100 GHz.