High Al-content AlGaN/GaN HEMTs on SiC substrates with very high power performance

With the promise of a new level of power performance at microwave frequencies, GaN-based high-mobility-transistors (HEMTs) have attracted sustained research effort and shown steadfast improvements. Previous state-of-the-art included power densities of 5.3-6.9 W/mm at 10 GHz from small devices, as well as a total output power of 9.1 W at 7.4 GHz from a 3-mm-wide device. This performance was obtained using AlGaN/GaN HEMTs grown on SiC substrates for superior heat dissipation. However, these devices used a low Al mole fraction of 14% in the AlGaN layer, which had been shown to be less preferred in an earlier study with devices grown on sapphire substrates. In this work, high Al content AlGaN/GaN HEMTs on SiC substrates are demonstrated with remarkable performance enhancement.