Impact of Charge-Trapping Effects on Reliability Instability in Al_xGa_1-xN/GaN High-Electron-Mobility Transistors with...

In this study, we present a detailed analysis of trapping characteristics at the Al_xGa_1-xN/GaN interface of Al_xGa_1-xN/GaN high-electron-mobility transistors (HEMTs) with reliability assessments, demonstrating how the composition of the Al in the Al_xGa_1-xN barrier impacts the performance of the device. Reliability instability assessment in two different Al_xGa_1-xN/GaN HEMTs [x = 0.25, 0.45] using a single-pulse I characterization technique revealed higher drain-current degradation (∆I) with pulse time for Al_0.45Ga_0.55N/GaN devices which correlates to the fast-transient charge-trapping in the defect sites near the interface of Al_xGa_1-xN/GaN. Constant voltage stress (CVS) measurement was used to analyze the charge-trapping phenomena of the channel carriers for long-term reliability testing. Al_0.45Ga_0.55N/GaN devices exhibited higher-threshold voltage shifting (∆V) caused by stress electric fields, verifying the interfacial deterioration phenomenon. Defect sites near the interface of the AlGaN barrier responded to the stress electric fields and captured channel electrons-resulting in these charging effects that could be partially reversed using recovery voltages. The quantitative extraction of volume trap density (N) using 1/f low-frequency noise characterizations unveiled a 40% reduced N for the Al_0.25Ga_0.75N/GaN device, further verifying the higher trapping phenomena in the Al_0.45Ga_0.55N barrier caused by the rougher Al_0.45Ga_0.55N/GaN interface.