600V增强型GaN HEMT器件研究及设计

发布时间：2018-05-06 21:19

本文选题：氮化镓 + HEMT　；参考：《东南大学》2016年硕士论文

【摘要】：作为第三代半导体材料,氮化镓(GaN)具有禁带宽度宽、临界击穿电场大以及电子饱和速度高等优点,且AlGaN/GaN异质结会在异质结界面处形成浓度较高的二维电子气(wo Dimensional Electron Gas, 2DEG),因此GaN高电子迁移率晶体管(High Electron Mobility Transistors, HEMT)适合作为功率器件。然而,常规的GaN HEMT器件为耗尽型器件,且由于GaN材料本身泄露电流较大,使得器件击穿电压不高,因此,为了将GaN HEMT器件应用于功率开关领域,高压增强型GaN HEMT器件研究意义重大。本文旨在设计性能优越的600V增强型GaN HEMT器件。首先,以p-GaN栅极GaN HEMT器件为基本结构,采用二维仿真软件SILVACO分析了p-GaN层、AlGaN势垒层、栅漏间距、AlGaN缓冲层等结构参数对器件转移特性、导通态IV特性、击穿特性以及电容特性的影响,从而得出优化的p-GaN栅极GaNHEMT器件结构；此外,还针对p-GaN栅极GaN HEMT器件阈值电压不够高的缺点,进一步提出了一种绝缘埋层GaN HEMT器件,使得器件的阈值电压提升了2.14倍。本文还对600V增强型GaN HEMT器件在较高漏极偏压下由于缓冲层缺陷所导致的电流崩塌效应展开了研究。研究表明,电子在栅极边缘强电场的作用下注入缓冲层并被缺陷捕获是造成电流崩塌效应的主要原因,高缺陷浓度和深能级缺陷都会导致电流崩塌效应加剧。最终,从减少注入缓冲层电子数目的角度出发,本文还提出了一种P型埋层结构,使得器件漏极电流减小的百分比从原本的11.0%降低至5.12%,显著减小了器件的电流崩塌效应。
[Abstract]:As the third generation semiconductor material, gallium nitride (gan) has the advantages of wide bandgap, high critical breakdown electric field and high electron saturation velocity. And AlGaN/GaN heterojunction can form high concentration two-dimensional electron gas at the heterojunction surface, so GaN high electron mobility transistor (GaN) is suitable for power devices. However, the conventional GaN HEMT device is a depleted device, and the breakdown voltage is not high because of the large leakage current of the GaN material. Therefore, in order to apply the GaN HEMT device to the power switch field, It is of great significance to study high voltage enhanced GaN HEMT devices. The purpose of this paper is to design 600 V enhanced GaN HEMT device. Firstly, with the p-GaN gate GaN HEMT device as the basic structure, the transfer characteristics and on-state IV characteristics of p-GaN layer and AlGaN buffer layer are analyzed by using the two-dimensional simulation software SILVACO, such as p-GaN layer and AlGaN buffer layer. The influence of breakdown characteristics and capacitance characteristics on the structure of p-GaN gate GaNHEMT devices is obtained. In addition, an insulating buried layer GaN HEMT device is proposed to overcome the disadvantage that the threshold voltage of p-GaN gate GaN HEMT devices is not high enough. The threshold voltage of the device is increased by 2.14 times. In this paper, the effect of current collapse caused by buffer layer defects in 600V enhanced GaN HEMT devices with high drain bias voltage is also studied. It is shown that the effect of current collapse is mainly caused by the injection of electrons into the buffer layer under the action of a strong electric field at the edge of the gate, and the effect of current collapse is aggravated by high defect concentration and deep level defect. Finally, from the point of view of reducing the number of electrons injected into the buffer layer, a P-type buried layer structure is proposed, which reduces the percentage of drain current decrease from 11.0% to 5.12%, which significantly reduces the current collapse effect of the device.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN386

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