Schottky Contact Degradation and Dislocations in AlGaN‐GaN HEMTs

GaN power amplifiers based on AlGaN‐GaN high electron mobility transistor (HEMT) technology are finding applications in space satellite systems that require high voltage, high power, and high efficiency operation. In recent years, leading GaN HEMT manufacturers have reported excellent performance characteristics, and several research groups have proposed degradation mechanisms, but their long‐term reliability especially under high electric field operation in space environments remains a major concern. For AlGaN‐GaN HEMTs to be successfully deployed in space satellite systems, their reliability and failure mechanisms need to be understood through the physics of failure investigation. Two types of HEMT structures are used to investigate i) a new failure mechanism—Schottky contact degradation in RF AlGaN‐GaN HEMTs with Ni‐Pd‐Au Schottky contact—and ii) effects of threading dislocations on electrical characteristics of DC AlGaN‐GaN HEMTs grown on semi‐insulating (SI) SiC and GaN substrates.