Abstract
In this study, we present a detailed analysis of trapping characteristics at the Al(x)Ga(1-x)N/GaN interface of Al(x)Ga(1-x)N/GaN high-electron-mobility transistors (HEMTs) with reliability assessments, demonstrating how the composition of the Al in the Al(x)Ga(1-x)N barrier impacts the performance of the device. Reliability instability assessment in two different Al(x)Ga(1-x)N/GaN HEMTs [x = 0.25, 0.45] using a single-pulse I(D)-V(D) characterization technique revealed higher drain-current degradation (∆I(D)) with pulse time for Al(0.45)Ga(0.55)N/GaN devices which correlates to the fast-transient charge-trapping in the defect sites near the interface of Al(x)Ga(1-x)N/GaN. Constant voltage stress (CVS) measurement was used to analyze the charge-trapping phenomena of the channel carriers for long-term reliability testing. Al(0.45)Ga(0.55)N/GaN devices exhibited higher-threshold voltage shifting (∆V(T)) 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(t)) using 1/f low-frequency noise characterizations unveiled a 40% reduced N(t) for the Al(0.25)Ga(0.75)N/GaN device, further verifying the higher trapping phenomena in the Al(0.45)Ga(0.55)N barrier caused by the rougher Al(0.45)Ga(0.55)N/GaN interface.