E-Mode AlN/GaN HEMTs on Si With 80.4% PAE at 3.6 GHz for Low-Supply-Voltage RF Power Applications

Enhancement-mode (E-mode) AlN/GaN high electron mobility transistors (HEMTs) with a 160-nm T- shape recessed gate on a silicon substrate were fabricated. The fabricated device has a V TH of + 0.35 V, and shows a maximum drain current (I DMAX ) of 1.58 A/mm, a low on- resistance (RON) of 1.8 Sl<middle dot> mm, and a peak transconductance (G MMAX ) over 580 mS/mm. A cut-off frequency (fT) of 85 GHz and a maximum oscillation frequency (fmax) of 75 GHz were obtained. Load pull continuous-wave (CW) power sweep measurement at 3.6 GHz demonstrated a peak power-added-efficiency (PAE) of 71.4% and a saturated output power density (Pout) of 0.70 W/mm at V DS = 6 V. At 3.6 GHz pulsed wave (PW) power sweep at V DS = 6 V the device demonstrated an 80.4% PAE and 0.5 W/mm associated Pout.These results promises the great potential of E-mode AlN/GaN HEMTs with gate recess in the applications of low supply voltage RF power applications.