High-performance 2 mm gate width GaN HEMTs on 6H-SiC with output power of 22.4 W @ 8 GHz

Abstract

Optimized AlGaN/AlN/GaN high electron mobility transistors (HEMTs) structures were grown on 2-in. semi-insulating (SI) 6H-SiC substrate by metal–organic chemical vapor deposition (MOCVD). The 2-in. HEMT wafer exhibited a low average sheet resistance of 305.3Ω/sq with a uniformity of 3.85%. The fabricated large periphery device with a dimension of 0.35μm×2mm demonstrated high performance, with a maximum DC current density of 1360mA/mm, a transconductance of 460mS/mm, a breakdown voltage larger than 80V, a current gain cut-off frequency of 24GHz and a maximum oscillation frequency of 34GHz. Under the condition of continuous-wave (CW) at 8GHz, the device achieved 18.1W output power with a power density of 9.05W/mm and power-added-efficiency (PAE) of 36.4%. While the corresponding results of pulse condition at 8GHz are 22.4W output power with 11.2W/mm power density and 45.3% PAE. These are the state-of-the-art power performance ever reported for this physical dimension of GaN HEMTs based on SiC substrate at 8GHz.