A New Differential Amplitude Spectrum for Analyzing the Trapping Effect in GaN HEMTs Based on the Drain Current Transient

Abstract

The reliability of GaN high-electron-mobility transistors remains limited by trapping, and a new way to characterize traps is through the drain current transient. In this paper, we report a differential amplitude spectrum (DAS) from which we could extract the exact amount that a trap contributes to charging/discharging from the current transient. We compared the time constant spectrum and the DAS in extracting traps' amplitudes theoretically and experimentally. Using the DAS, we investigated the trapping effect and systematically identified the positions and mechanisms of traps with E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> values of 0.10, 0.38, 0.45, and 0.61 eV in our samples. In particular, we demonstrated that the semi-ON state with high-drain voltage in the filling process can maximize the charge trapping in both the AlGaN layer and GaN buffer. In addition, we experimentally proved that measured voltage in the linear region was the best choice for these samples.