Effect of the High-Temperature Off-State Stresses on the Degradation of AlGaN/GaN HEMTs

Jinfu Lin,Hongxia Liu,Shulong Wang,Lei Wu,Chang Liu,Mengyu Li

doi:10.3390/electronics8111339

Abstract

GaN-based high electron mobility transistors offer high carrier density combined with high electron mobility and often require operation at high frequencies, voltages, and temperatures. The device may be under high temperature and high voltage at the same time in actual operation. In this work, the impact of separate off-state stresses, separate high-temperature stresses, and off-state stresses at high temperatures on AlGaN/GaN high electron mobility transistors (HEMTs) grown on Si substrates was investigated. The output current and gate leakage of the device degenerated to different degrees under either isolated off-state or high-temperature stress. The threshold voltage of the device only exhibited obvious negative drift under the action of high-temperature and off-state stresses. The parameter at high temperature (or room temperature) before stress application was the reference. We found that there was no significant difference in the degradation rate of drain current and transconductance peak when the same off-state stress was applied to the device at different temperatures. It was concluded that, under the high-temperature off-state electric field pressure, there were two degradation mechanisms: one was the inverse piezoelectric polarization mechanism only related to the electric field, and the other was the degradation mechanism of the simultaneous action of temperature and electric field.

Highlights

GaN-based high electron mobility transistors (HEMTs) are excellent candidates for high-frequency, high-field, and high-temperature applications in the microwave range, due to their large band gap, high breakdown electric field, and high mobility two-dimensional electron gas (2DEG) [1,2,3]
We studied the degradation of the sample device under separate off-state stresses, separate high-temperature stresses, and off-state stresses at high temperatures, in order to compare and study the parameter changes of the device when the temperature stress and the electric stress existed at the same time, and analyze the cause of the change
The AlGaN/GaN HEMT device used in this experiment adopted a standard process

Summary

Introduction

GaN-based high electron mobility transistors (HEMTs) are excellent candidates for high-frequency, high-field, and high-temperature applications in the microwave range, due to their large band gap, high breakdown electric field, and high mobility two-dimensional electron gas (2DEG) [1,2,3]. High-field degradation characteristics refer to the possible degradation effect of AlGaN/GaN. The primary explanation for the degradation of AlGaN/GaN HEMT devices under strong electric field stress is the thermionic electron effect. The thermionic electron will lead to the capture and generation of surface state traps between the gate and drain, affecting the performance of devices and causing device degradation. The device lacks channel thermal electrons under the off-state stress of the large electric field. It is suggested that there may be other mechanisms for degradation of the device under off-state stress

Methods

Results

Conclusion