Gallium nitride (GaN)-based power devices enable high power density and high switching frequency for power electronics systems. For the emerging vertical GaN devices, the electric field crowding around the edge of the main junction could result in premature breakdown. It is challenging to employ the commonly used junction-based termination techniques as in Si and SiC high-voltage devices for vertical GaN devices, due to the difficulty of selective p-type doping and activation in GaN. In this work, based on the unique feature of the negatively charged F ions in GaN which can favorably modulate the edge electric field, a fluorine-implanted termination (FIT) structure for vertical GaN PiN diodes has been designed and optimized to suppress the electric field crowding at the junction edge for a higher breakdown voltage (BV). The key parameters of the FIT, including the F ion dose, the thickness and width of the FIT and the angle of the bevel structure, have been comprehensively investigated by TCAD simulations to reveal their impacts on BV. Moreover, with a tapered dose distribution in the FIT, the device can achieve a higher BV with an enlarged FIT dose window.

中文翻译：

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具有注入氟终端的垂直 GaN PiN 二极管的设计和优化

基于氮化镓 (GaN) 的功率器件可为电力电子系统提供高功率密度和高开关频率。对于新兴的垂直 GaN 器件，主结边缘周围的电场可能会导致过早击穿。由于 GaN 中选择性 p 型掺杂和激活的困难，将常用的基于结的端接技术用于垂直 GaN 器件的 Si 和 SiC 高压器件具有挑战性。在这项工作中，基于 GaN 中带负电的 F 离子的独特特性，可以有利地调节边缘电场，设计并优化了垂直 GaN PiN 二极管的氟注入终端 (FIT) 结构以抑制电场在结边缘拥挤以获得更高的击穿电压 (BV)。FIT 的关键参数，包括 F 离子剂量、FIT 的厚度和宽度以及斜面结构的角度，已经通过 TCAD 模拟进行了全面研究，以揭示它们对 BV 的影响。此外，通过 FIT 中的锥形剂量分布，该装置可以通过扩大的 FIT 剂量窗口实现更高的 BV。