High-permittivity dielectric edge termination for vertical high voltage devices
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High‑permittivity dielectric edge termination for vertical high voltage devices Hyun‑Soo Lee1 · Nidhin Kurian Kalarickal1 · Mohammad Wahidur Rahman1 · Zhanbo Xia1 · Wyatt Moore1 · Caiyu Wang1 · Siddharth Rajan1 Received: 25 March 2020 / Accepted: 18 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract A novel edge-termination concept using extreme permittivity dielectrics is proposed to effectively manage electric fields in vertical power-devices. This method is expected to be particularly significant for wide band-gap semiconductors, where field termination is a significant challenge due to material and process limitations. Detailed two-dimensional device simulation is used to prove the efficacy of this idea, and to demonstrate that peak electric fields are significantly reduced by this method. We also show an analytical model that gives an intuitive picture into the mechanism of high-permittivity dielectric field plate. Low process complexity and flexibility in the design of power devices can be achieved. We show that junction termination efficiency can be increased from 22.7% (no junction termination) and 50% (conventional field plate) to 73% (high-permittivity-terminated device). Keywords Power devices · Vertical power device · Edge termination · Field plate · High-K dielectric
1 Introduction Gallium nitride (GaN)-based devices are promising for high frequency and power applications because they have a superior combination of critical electric field, electron mobility, saturation drift velocity, and power density [1]. With recent interest in solid-state power electronics technologies with operating voltages higher than 1 kV, there is a need to design highly efficient power devices with low resistance and switching losses [2]. The vertical device topology is preferred for several applications since it allows for the high current injection necessary in such high power systems. In addition, high voltage planar junctions under reverse bias exhibit significantly lower breakdown voltages than in the ideal case due to effects of field crowding at the junction periphery [3]. Thus, edge termination technique is considerably important for power devices to achieve closer expected ideal breakdown voltage and specific on resistance. There * Hyun‑Soo Lee [email protected] * Siddharth Rajan [email protected] 1
The Electrical and Computer Engineering Department, The Ohio State University, Columbus, OH 43210, USA
were a tremendous of previous research for obtaining effective and easy edge termination techniques in power device field such as guard ring (GR) [4–6] and junction termination extension structures (JTE) [7–9]. In order to achieve higher breakdown voltage efficiency, precise and additional processing is necessary. However, patterned p-type doping, which is used to achieve edge termination in other material technologies such as Si and SiC, has been challenging for GaN, Ga2O3 due to the absence of an efficient and reliable patterned doping process, although progress has been ma
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