Two-Step Mesa Structure GaN p-n Diodes With Low ON-Resistance, High Breakdown Voltage, and Excellent Avalanche Capabilities
Two-Step Mesa Structure GaN p-n Diodes With Low ON-Resistance, High Breakdown Voltage, and Excellent Avalanche Capabilities
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DOI：
10.1109/led.2019.2955720
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发表时间：
2020-01-01
影响因子：
4.9
通讯作者：
Mishima, Tomoyoshi
中科院分区：
文献类型：
--
作者：
Ohta, Hiroshi;Asai, Naomi;Mishima, Tomoyoshi
在独立GaN衬底上制造的垂直结构GaN功率器件在理想高效的能量转换系统中具有很高的潜力。这封信描述了高击穿电压GaN p-n结二极管的高雪崩能力的成功收购。我们已经报道了通过在p-GaN层中应用穿通结构的高雪崩能力，然而，该结构引起了导通电阻和导通电压增加的缺点。通过应用一种新开发的两步梅萨结构组成的第一个内部梅萨与部分减薄的p-GaN层和第二个外部梅萨蚀刻到n-GaN漂移层，具有可逆的电流-电压特性的高雪崩能力已实现在4.7-4.8 kV的高击穿电压，而不牺牲正向I-V特性。两级梅萨结构将p-n结中的峰值电场位置从干法刻蚀损伤的第二外梅萨转移到被减薄的p-GaN层覆盖的第一梅萨，从而导致轻微击穿。无论阳极电极直径如何，都以良好的再现性获得了高雪崩能力。这种结构可以有助于鲁棒电力系统的建设。
Vertical structure GaN power devices fabricated on freestanding GaN substrates have high potentials in ideally efficient energy conversion systems. This letter describes successful acquisition of high avalanche capabilities for high breakdown voltage GaN p-n junction diodes. We have already reported the high avalanche capability by applying a punch-through structure in p-GaN layer, however; the structure caused a drawback of increase in on-resistance and turn-on voltage. By applying a newly developed two-step mesa structure consisting of the first inner mesa with partially thinned p-GaN layer and the second outer mesa etched to n-GaN drift layer, the high avalanche capabilities with reversible current-voltage characteristics have been realized at high breakdown voltages of 4.7-4.8 kV without sacrificing the forward I-V characteristics. The two-step mesa structure transferred the position of the peak electric field in the p-n junction from the dry-etch damaged second outer mesa to the first mesa covered by the thinned p-GaN layer, which could lead the mild breakdown. The high avalanche capability was obtained with good reproducibility regardless of the anode electrode diameter. This structure can contribute to the construction of robust power systems.