AlGaN/GaN HEMTs on Si by MBE with regrown contacts and fT = 153 GHz



AlGaN/GaN high-electron-mobility transistors (HEMT) have been grown by radio frequency molecular beam epi-taxy (RF-MBE) on 3″ Si substrates. A record low contact resistance Rc ˜ 0.11 Ω.mm has been achieved for GaN HEMTs on Si by using non alloyed ohmic contacts regrown by MBE. Owing to the low contact resistance a 75-nm gate length unpassivated HEMT shows intrinsic current gain cut-off frequency fT =153 GHz, a high saturation drain current density> 1.3 A/mm and a low RON of 1 Ω.mm, among the best reported for HEMTs on Si. With further scaling GaN HEMTs on Si can compete in the high-performance RF arena with similar devices on SiC, while exploiting the many advantages of integration with Si. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)