Reliability Instability Assessment with Interfacial Trapping Analysis for the Optimization of Al Composition in Al_xGa_1-xN/GaN High Electron Mobility Transistors

This study investigates the trapping characteristics present at the interface of AlxGa1-xN/GaN high electron mobility transistors (HEMTs) and explores the influence of the Al composition within the AlxGa1-xN barrier on the device's performance. Using a single pulse I-D-V-D characterization technique, the reliability instability is evaluated in two different AlxGa1-xN/GaN HEMTs: one with an Al composition of 25% (Al0.25Ga0.75N/GaN) and the other with an Al composition of 45% (Al0.45Ga0.55N/GaN). The results unveil a notable higher drain current degradation (Delta I-D) in Al0.45Ga0.55N/GaN devices, attributed to fast transient charge trapping. Conversely, the Al0.25Ga0.75N/GaN device exhibits a substantial 35% reduction in interface trap density (D-it) and an impressive 73% decrease in border trap density (N-bt), solidifying its reduced trapping behavior compared to Al0.45Ga0.55N/GaN due to the rougher barrier/channel interface of the latter device. Furthermore, load-pull measurements unveiled a noteworthy 60% power-added efficiency for the Al0.25Ga0.75N/GaN device, presenting a 10% performance improvement over the Al0.45Ga0.55N/GaN device. These findings provide valuable insights into the trapping phenomena within AlGaN/GaN HEMTs, paving the way for enhanced device design and performance optimization.