Abstract
To enhance the RF power properties of CMOS-compatible gold-free GaN devices, this work introduces a kind of GaN-on-Si HEMT with a low parasitic regrown ohmic contact technology. Attributed to the highly doped n(+) InGaN regrown layer and smooth morphology of gold-free ohmic stacks, the lowest ohmic contact resistance (R(c)) was presented as 0.072 Ω·mm. More importantly, low RF loss and low total dislocation density (TDD) of the Si-based GaN epitaxy were achieved by a designed two-step-graded (TSG) transition structure for the use of scaling-down devices in high-frequency applications. Finally, the fabricated GaN HEMTs on the Si substrate presented a maximum drain current (I(drain)) of 1206 mA/mm, a peak transconductance (G(m)) of 391 mS/mm, and a breakdown voltage (V(BR)) of 169 V. The outstanding material and DC performances strongly encourage a maximum output power density (P(out)) of 10.2 W/mm at 8 GHz and drain voltage (V(drain)) of 50 V in active pulse mode, which, to our best knowledge, updates the highest power level for gold-free GaN devices on Si substrates. The power results reflect the reliable potential of low parasitic regrown ohmic contact technology for future large-scale CMOS-integrated circuits in RF applications.