GaN HEMTs on Si With Regrown Contacts and Cutoff/Maximum Oscillation Frequencies of 250/204 GHz

This work demonstrates the high-frequency and high-power performance capacity of GaN high electron mobility transistors (HEMTs) on Si substrates. Using a T-gate and
${n}^{++}$
-GaN source/drain contacts, the InAlN/GaN HEMT with a gate length of 55 nm and a source-drain spacing of 175 nm shows a maximum drain current
${I}_{{D,MAX}}$
of 2.8 A/mm and a peak transconductance
${g}_{m}$
of 0.66 S/mm. The same HEMT exhibits a forward-current-gain cutoff frequency
${f}_{T}$
of 250 GHz and a maximum frequency of oscillation
${f}_{{MAX}}$
of 204 GHz. The
${I}_{{D,MAX}}$
, peak
${g}_{m}$
and
${f}_{T} -{f}_{{MAX}}$
product are among the best reported for GaN HEMTs on Si, which are very close to the state-of-the-art depletion-mode GaN HEMTs on SiC without a back barrier. Given the low cost of Si and the high compatibility with CMOS circuits, GaN HEMTs on Si prove to be particularly attractive for cost-sensitive applications.