GaN-on-Si HEMTs Fabricated With Si CMOS-Compatible Metallization for Power Amplifiers in Low-Power Mobile SoCs

GaN-on-Si high electron mobility transistors (HEMTs) were fabricated using Si CMOS-compatible metallization scheme for RF power amplifiers (PAs)in 5G low-power mobile system-on-chips (SoCs). Ta/Al metals were adopted for the ohmic contact formation. The device with 80-nm rectangular gate exhibited a drain current ( $I_{d\mathrm {max}}$ ) of 1.95 A/mm, a peak transconductance ( $g_{m}$ ) of 471 mS/mm, a cutoff frequency ( $f_{T}$ ) of 178 GHz, and a maximum oscillation frequency ( $f_{\mathrm {max}}$ ) of 74 GHz. At a mobile SoC-compatible supply voltage of $V_{d} = 5$ V, the device shows a peak power-added efficiency (PAE) of 51.4%/47.6%, a maximum output power density ( $P_{\mathrm {outmax}}$ ) of 1.12 W/mm/1.06 W/mm, and a gain of 16 dB/16 dB at frequency of 3.5 GHz/5 GHz, respectively. These results indicate the great potential of the GaN-on-Si HEMTs for high-performance and low-cost RF PAs for 5G mobile SoC applications.