AlGaN-GaN HEMTs on patterned silicon (111) substrate

We report the AlGaN-GaN high-electron mobility transistors (HEMTs) grown and fabricated on patterned silicon (111) substrates. A crack-free AlGaN-GaN HEMT heterostructure was grown on top of rectangular silicon ridges patterned on the silicon substrate. Fabrication of HEMT on the ridges was demonstrated using a polyimide planarization process. Maximum drain current density of 1.05 A/mm and peak transconductance of 150 mS/mm were achieved with 1.0 μm gate-length. The current gain cutoff frequency and maximum frequency of oscillation were 9.7 and 20.5 GHz, respectively, for the 1 μm × 300 μm devices.