Center for Power Electronics Systems
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Browsing Center for Power Electronics Systems by Subject "breakdown voltage"
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- 1 kV GaN-on-Si Quasi-Vertical Schottky RectifierQin, Yuan; Xiao, Ming; Zhang, Ruizhe; Xie, Qingyun; Palacios, Tomás; Wang, Boyan; Ma, Yunwei; Kravchenko, Ivan; Briggs, Dayrl P.; Hensley, Dale K.; Srijanto, Bernadeta R.; Zhang, Yuhao (IEEE, 2023-07)This work demonstrates quasi-vertical GaN Schottky barrier diodes (SBDs) on 6-inch Si substrate with a breakdown voltage (BV) over 1 kV, the highest BV reported in vertical GaN-on-Si SBDs to date. The deep mesa inherently in quasi-vertical devices is leveraged to form a self-aligned edge termination, and the mesa sidewall is covered by the p-type nickel oxide (NiO) as a reduced surface field (RESURF) structure. This novel termination enables a parallel-plane junction electric field of 2.8 MV/cm. The device also shows low turn-on voltage of 0.5 V, and low specific on-resistance of 1.1 m ·cm2. Moreover, the device exhibits excellent overvoltage robustness under the continuous 800 V stress in the unclamped inductive switching test. These results show the good promise of the low-cost vertical GaN-on-Si power diodes.
- Dynamic Gate Breakdown of p-Gate GaN HEMTs in Inductive Power SwitchingWang, Bixuan; Zhang, Ruizhe; Wang, Hengyu; He, Quanbo; Song, Qihao; Li, Qiang; Udrea, Florin; Zhang, Yuhao (IEEE, 2023-02)We employ a new circuit method to characterize the gate dynamic breakdown voltage (BVdyn) of Schottky-type p-gate GaN HEMTs in power converters. Different from prior pulse I-V and DC stress tests, this method features a resonance-like gate ringing with the pulse width down to 20 ns and an inductive switching concurrently in the drain-source loop. At the increased pulse width, the gate BVdyn shows a decrease and then saturation at 21~22 V. Moreover, the gate BVdyn increases with temperature and is higher under the hard switching than that under the drain-source grounding condition. In the 400 V hard switching at 150 oC, the gate BVdyn reaches 27.5 V. Such impact of the drain switching locus and temperature on the gate BVdyn is not seen in Si and SiC power transistors tested in the same setup. These results are explained by a physics model that accounts for the electrostatics in the p-GaN gate stack in hard switching and at high temperatures. This work unveils new physics critical to the gate robustness of p-gate GaN HEMTs and manifest the necessity of the gate robustness evaluation in inductive switching conditions.
- Power device breakdown mechanism and characterization: review and perspectiveZhang, Ruizhe; Zhang, Yuhao (IOP Publishing, 2023-04)Breakdown voltage (BV) is arguably one of the most critical parameters for power devices. While avalanche breakdown is prevailing in silicon and silicon carbide devices, it is lacking in many wide bandgap (WBG) and ultra-wide bandgap (UWBG) devices, such as the gallium nitride high electron mobility transistor and existing UWBG devices, due to the deployment of junction-less device structures or the inherent material challenges of forming p-n junctions. This paper starts with a survey of avalanche and non-avalanche breakdown mechanisms in WBG and UWBG devices, followed by the distinction between the static and dynamic BV. Various BV characterization methods, including the static and pulse I-V sweep, unclamped and clamped inductive switching, as well as continuous overvoltage switching, are comparatively introduced. The device physics behind the time- and frequency-dependent BV as well as the enabling device structures for avalanche breakdown are also discussed. The paper concludes by identifying research gaps for understanding the breakdown of WBG and UWBG power devices.