DC and RF Performance of AlGaN/GaN HEMTs on SiC at High Temperatures

GaN-based transistors have demonstrated to be the most promising candidates for applications with high power and high frequency requirements, and working in harsh environments. They take advantage of some interesting properties of nitrides such as their thermal stability or high electron velocity, together with a high sheet carrier density (~1013 cm-2) provided by AlGaN/GaN heterostructures thanks to the favorable band offsets and internal piezoelectric fields. In above applications, transistors may work in small signal amplifiers under high ambient temperatures, or in power amplifiers where channel temperatures may increase significantly. Thus, high temperature (HT) operation and related reliability issues have become important research topics in GaN electronics. Although some works have been recently published about DC characterization of HEMTs at HT [1-5], there are few papers studying their behaviour at RF [4,5]. This work aims to understand the small signal performance of AlGaN/GaN HEMTs on SiC at HT, using DC and RF measurements combined with proper modeling and small signal parameters extraction