1. Characterization of Threshold Voltage Instability Under Off-State Drain Stress and Its Impact on p-GaN HEMT Performance
- Author
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Chi Xu, Fei Yang, and Bilal Akin
- Subjects
010302 applied physics ,Physics ,Condensed matter physics ,020208 electrical & electronic engineering ,Transistor ,Energy Engineering and Power Technology ,Gallium nitride ,02 engineering and technology ,High-electron-mobility transistor ,01 natural sciences ,Omega ,law.invention ,Threshold voltage ,Stress (mechanics) ,chemistry.chemical_compound ,chemistry ,law ,Logic gate ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Voltage - Abstract
The $p$ -GaN gate technology is commonly implemented to achieve normally OFF gallium nitride (GaN) devices. Nonetheless, the threshold voltage instability under OFF-state stress remains a concern. In this article, the characterization technique of threshold voltage shift is proposed and the $V_{\text {th}}$ shift’s impact on device performance is investigated. Specifically, a fast $V_{\mathrm {th}}$ the measurement circuit is introduced and validated to successfully characterize both the magnitude and the time-constant of the $V_{\mathrm {th}}$ shift. According to the experimental results, the $V_{\mathrm {th}}$ increases by more than 50% within several $\mu \text{s}$ after the high drain voltage is applied. In contrast, the $V_{\mathrm {th}}$ slowly (tens of seconds) gets back to the static value after the stress is removed. Following the characterization, the threshold voltage instability’s impact on the device’s static/switching performance is studied experimentally. A knee point shift is observed at low gate voltage, and the static ON-resistance value remains unchanged. Regarding the switching performance, the turn-ON loss increases by >20% after the high drain voltage stress. The change in turn-ON loss can be reduced when the gate resistance is decreased from 20 to $0~\Omega $ . In terms of the turn-OFF loss, the impact of the $V_{\mathrm {th}}$ shift is negligible. It is concluded that time-dependent threshold voltage shift needs to be considered in $p$ -GaN device’s modeling, and high gate drive voltage together with low gate resistance is recommended to mitigate the $V_{\mathrm {th}}$ instability’s effect on $p$ -GaN high-electron-mobility transistor’s performance.
- Published
- 2021