AlGaN/GaN High Electron Mobility Transistors Grown by MOVPE on 3C-SiC/Si(111) for RF Applications

In this work, an AlGaN/GaN HEMT structure is grown on a 0.8 μm thick 3C-SiC layer on high resistivity Silicon substrate. The RF propagation losses are investigated and compared with the ones of epi-layers grown directly on Silicon and on 6H-SiC substrates. Short gate length transistors are fabricated using e-beam lithography. In spite of ohmic contact resistance of 0.6 Ω.mm, a saturated current density of 0.7 A/mm at a gate bias of +1V and a transconductance peak higher to 250 mS/mm for 75 nm T-shaped gate transistors are reached on structure with thick 3C-SiC template. Moreover, for the first time, transition frequencies fT/fmax of 60/98 GHz are reported on such 3C-SiC template.