Low-Damage Interface Enhancement-mode AlN/GaN HEMTs with 41.6% PAE at 30 GHz

Abstract This paper reports a low-damage interface treatment process for AlN/GaN high-electron-mobility transistors (HEMTs) and demonstrates the excellent power characteristics of radio frequency (RF) enhancement-mode (E-mode) AlN/GaN HEMTs. An RF E-mode device fabricated by remote plasma oxidation (RPO) treatment with 2.9-nm AlN barrier layer at 300 ℃. The device with a gate length of 0.12-μm has a threshold voltage (Vth) of 0.5 V, a maximum saturation current of 1.16 A/mm, a high Ion/Ioff ratio of 1*108, and a 440 mS/mm peak transconductance. During continuous wave (CW) power testing, it demonstrated a power added efficiency of 61.9% and a power density of 1.38 W/mm at 3.6 GHz, and a power added efficiency of 41.6% and a power density of 0.85 W/mm at 30 GHz. Furthermore, RPO treatment improves the mobility of RF E-mode AlN/GaN HEMTs. All results show that the RPO processing method has good applicability for scaling ultrathin barrier E-mode AlN/GaN HEMTs for 5G compliable frequency ranging from sub-6 GHz to Ka-band.