GaN基HEMT器件的性能研究与设计优化

发布时间：2018-07-20 12:24

【摘要】：宽禁带半导体Ga N(氮化镓)是目前在高温、高频、大功率微波领域等飞速发展的第三代半导体材料的代表。它具有热导率高、击穿场强高、电子漂移速率高、耐高温、耐腐蚀、以及化学性质稳定等优点。与Ga As(砷化镓)以及Si(硅)等前两代半导体材料相比,氮化镓这些特有的优异性能使其广泛应用于高温、高频、大功率、光电子等领域。本工作首先简单地介绍了Ga N基HEMT在国内外的发展历史以及研究现状,概括了氮化镓材料的特性及特征,并且系统地介绍了Al Ga N/Ga N HEMT的原理与结构。文章突出描述了Al Ga N/Ga N异质结所特有的二维电子气以及极化效应,并对其存在的原理进行了研究。本工作的研究核心是利用ATLAS软件建立Al Ga N/Ga N HEMT的器件模型,通过合理地改变器件栅漏间距、栅长等参数及有无场板、衬底组成等结构,来进行Al Ga N/Ga N HEMT性能的模拟研究。通过模拟表明Al Ga N/Ga N HEMT器件性能与栅漏间距、栅长、场板结构、衬底材料、自热效应等之间的关系,并通过对得到的模拟结果进行深入的讨论和分析得到优化的器件设计。结果表明:减小栅长,可以减小器件的阈值电压,增大器件的漏极电流,从而改善器件的I-V特性和转移特性;栅漏间距直接影响着器件的等效电阻,在线性区,栅漏间距越大漏极电流就越小,但栅漏间距不影响饱和区电流和阈值电压;场板结构可以减小器件的漏极电流,增大器件的击穿电压并能有效地抑制电流崩塌效应;作为衬底材料蓝宝石比Si及金刚石组成的衬底自热效应更加严重;同时Si及金刚石组成的衬底中减小Si层的厚度有利于减小器件的自热效应,降低有源区最高温度。由于Al Ga N/Ga N HEMT的研究还不成熟,电流崩塌效应、自热效应等问题的存在会导致Al Ga N/Ga N HEMT器件的退化和失效,本文通过改变器件参数及尺寸以及器件结构优化了Ga N基HEMT器件的设计,达到了提高器件性能的目的。
[Abstract]:Gan (wide band gap semiconductor) is the representative of the third generation semiconductor materials which are developing rapidly in the field of high temperature, high frequency, high power microwave and so on. It has the advantages of high thermal conductivity, high breakdown field strength, high electron drift rate, high temperature resistance, corrosion resistance and chemical stability. Compared with GaAs (GaAs) and Si (Si) semiconductors, gallium nitride is widely used in the fields of high temperature, high frequency, high power, optoelectronics and so on. Firstly, the development history and research status of gan based HEMT at home and abroad are briefly introduced, the characteristics and characteristics of gan materials are summarized, and the principle and structure of Al Ga N / Ga N HEMT are systematically introduced. In this paper, the unique two-dimensional electron gas and polarization effects of Al Ga N / Ga N heterojunction are described, and the principle of their existence is studied. The core of this work is to establish the device model of Al Ga N / Ga N HEMT by using ATLAS software, and to simulate and study the performance of Al Ga N / Ga N HEMT by reasonably changing the gate leakage distance, gate length, structure of field board and substrate composition. The simulation results show the relationship between the performance of Al Ga N / Ga N HEMT devices and gate leakage spacing, gate length, field plate structure, substrate material, self-heating effect, etc. The optimized device design is obtained by in-depth discussion and analysis of the simulation results. The results show that decreasing the gate length can reduce the threshold voltage of the device and increase the drain current of the device, thus improving the I-V characteristic and the transfer characteristic of the device, and the gap between the gate and the drain directly affects the equivalent resistance of the device in the linear region. The larger the gate leakage distance, the smaller the drain current, but the gap does not affect the saturation current and threshold voltage, the field plate structure can reduce the drain current, increase the breakdown voltage and effectively suppress the current collapse effect. The self-heating effect of sapphire substrate is more serious than that of Si and diamond, and decreasing the thickness of Si layer in the substrate composed of Si and diamond can reduce the self-heating effect of the device and reduce the maximum temperature in the active region. Due to the immature study of Al Ga N / Ga N HEMT, the problems of current collapse and self-heating effect will lead to the degradation and failure of Al Ga N / Ga N HEMT devices. In this paper, the design of gan based HEMT device is optimized by changing the device parameters and size as well as the device structure. The purpose of improving the performance of the device is achieved.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386

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