High transconductance AlGaN/GaN HEMT with thin barrier on Si(111) substrate

The fabrication of high transconductance AlGaN/GaN high electron mobility transistors (HEMTs) grown on high-resistivity silicon substrate is reported with an AlGaN barrier thickness of only 12.5 nm. A maximum DC current density of 655 mA/mm, a current gain cutoff frequency (F
_T
) of 75 GHz and a power-gain cutoff frequency (F
_MAX
) of 125 GHz are obtained for a 0.125 μm gate length transistor. The device provides a record peak extrinsic transconductance of 332 mS/mm and an intrinsic value of 509 mS/mm. To the authors' knowledge, the obtained transconductances are the highest reported values from AlGaN/GaN devices grown on a Si(111) substrate. This performance demonstrates the potential of GaN transistors on silicon for low-cost microwave power applications.