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 f
_t-ext
= 104 GHz and f
_t-int
= 113 GHz. The high performance is attributed to the combination of low R
_sh
~ 230 Ω/sq (μ ~ 1079 cm
²
/V · s, n
_s
~ 2.39 × 10
¹³
cm
^-2
) and thin ~110-Å total barrier thickness with a short gate length. Other device parameters include R
_c
= 0.29 Ω · mm, I
_g,leak
= 27.9 μA/mm, g
_m,peak
= 432 mS/mm, and V
_th
= -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.