Deep level transient spectroscopy: Tracing interface and bulk trap‐induced degradation in AlGaN/GaN‐heterostructure based devices

Abstract The exceptional physical properties of gallium nitride (GaN) position GaN‐based power devices as leading candidates for next‐generation high‐efficiency smart power conversion systems. However, GaN's multi‐component nature results in a high density of epitaxial defects, whereas the introduction of dielectric layers further contributes to severe interface states and dielectric traps. These factors collectively impair reliability, manifesting as threshold voltage instability and current collapse, which pose significant barriers to the advancement of GaN‐based electronics. Establishing the intrinsic relationship between device reliability and defects is crucial for understanding and addressing reliability degradation issue. Deep level transient spectroscopy (DLTS) offers valuable insights by revealing defect‐induced changes in electrical parameters during the capture and emission processes under varying biases, thereby elucidating the influence of defects from GaN buffer layers, AlGaN barriers, dielectric layer, and even at dielectric/(Al)GaN interfaces. This research aims to provide a foundational understanding of reliability degradation whereas further enabling enhancements in device performance from the perspectives of epitaxial growth and process preparation, ultimately striving to improve the reliability of GaN‐based devices and unlock their full potential for practical applications.