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

Abstract

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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dmax</sub> ) of 1.95 A/mm, a peak transconductance (g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> ) of 471 mS/mm, a cutoff frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) of 178 GHz, and a maximum oscillation frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ) of 74 GHz. At a mobile SoC-compatible supply voltage of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> = 5 V, the device shows a peak power-added efficiency (PAE) of 51.4%/47.6%, a maximum output power density (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">outmax</sub> ) 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.