Abstract
In this study, we investigate the degradation characteristics of E-mode GaN High Electron Mobility Transistors (HEMTs) with a p-GaN gate by designed pulsed and prolonged negative gate (VGS) bias stress. Device transfer and transconductance, output, and gate-leakage characteristics were studied in detail, before and after each pulsed and prolonged negative VGS bias stress. We found that the gradual degradation of electrical parameters, such as threshold voltage (VTH) shift, on-state resistance (RDS-ON) increase, transconductance max (Gm, max) decrease, and gate leakage current (IGS-Leakage) increase, is caused by negative VGS bias stress time evolution and magnitude of stress voltage. The significance of electron trapping effects was revealed from the VTH shift or instability and other parameter degradation under different stress voltages. The degradation mechanism behind the DC characteristics could be assigned to the formation of hole deficiency at p-GaN region and trapping process at the p-GaN/AlGaN hetero-interface, which induces a change in the electric potential distribution at the gate region. The design and application of E-mode GaN with p-GaN gate power devices still need such a reliability investigation for significant credibility.
Highlights
IntroductionHigh electron mobility transistors (HEMTs) based on Gallium Nitride (GaN) are certainly becoming superior devices for high-frequency, high-voltage, and high-power applications with respect to their excellent physical properties [1] such as wide bandgap (3.4 eV), high breakdown voltage (3.3 MV/cm), and low permittivity
This study aims to investigate the physical mechanisms behind the electrical parameter instabilities of the E-mode Gallium Nitride (GaN) with p-GaN under negative gate (VGS ) bias stress
In the pulsed negative VGS bias stress experiment, we studied the effect of pulsed negative gate bias stress conditions from the device parameter instability and degradation
Summary
High electron mobility transistors (HEMTs) based on Gallium Nitride (GaN) are certainly becoming superior devices for high-frequency, high-voltage, and high-power applications with respect to their excellent physical properties [1] such as wide bandgap (3.4 eV), high breakdown voltage (3.3 MV/cm), and low permittivity. HEMT devices have low on-resistance [2], high power densities [3], and high breakdown voltages [4], which help design compact high-power RF and high-efficiency amplifiers [5]. These excellent device performances are obtained with an AlGaN/GaN hetero-junction and the formation of a 2-dimensional electron gas (2DEG)
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