15 W AlGaN/GaN Heterojunction FET on Sapphire Substrate

Abstract

AlGaN/GaN heterojunction FETs (HJFETs) on a thinned sapphire substrate are demonstrated with improved power capability. A 16 mm wide unpassivated HJFET on a 50 μm thick sapphire demonstrated 15.9 W cw saturated output power, 9.0 dB linear gain, and 29.1% power-added efficiency (PAE) at 34 V drain bias. Also, an 8 mm wide SiN-passivated HJFET on a 50 μm thick sapphire exhibited 11.9 W cw saturated output power, 13.3 dB linear gain, and 49.7% PAE at 26 V drain bias. The 15.9 W result is the highest total power achieved for GaN FETs on sapphire, establishing the validity of the GaN-on-thinned-sapphire technology.