Identification of Traps in p-GaN Gate HEMTs During OFF-State Stress by Current Transient Method

In this work, the current transient method was conducted for trap analysis in the p-GaN gate high-electron-mobility transistors (HEMTs) in the OFF-state. Based on the traditional detrapping transient measurements, the pure recovery transients can be isolated by subtracting the undetected part caused by the measurement conditions. A comparison of the measured and actual recovery transients under different drain filling voltages was presented. It suggested that this method can be effective to analyze the unregular transient curves and distinguish the charge trapping type preliminarily. In addition, three traps were identified based on the time constant spectra and the hidden absolute amplitudes of traps can be corrected using the differential amplitude spectra. The information of trap levels in the buffer layer and AlGaN barrier layer was revealed, consisting of three electron traps with energy levels of 0.313, 0.265, and 0.467 eV. The identification of the traps may provide a physical foundation for better understanding of the drain-induced trapping effect during the OFF-state in p-GaN HEMTs.

I. Introduction

GaN-based high-electron-mobility transistors (HEMTs) have become promising candidates for the next-generation switching systems due to the superior characteristics [1]–[4]. In practical applications, the normally-OFF HEMTs are more preferred for the low static power dissipation [5], simplified gate control scheme [6], and fail-safe operation [7]. In particular, the Schottky type p-GaN gate HEMTs have been commercialized in the power electronics market because of the low switching loss and fast switching capability [8]. Nevertheless, the p-GaN gate HEMTs still suffer from critical reliability concerns, such as threshold voltage () instability and trapping effect [3], [8], and more efforts should be devoted to investigating the degradation of dynamic properties.