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 epitaxy (RF-MBE) on 3” Si substrates. A record low contact resistance Rc ~ 0.11 .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 .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.