毫米波GaN HEMT物理模型研究

发布时间：2018-06-10 05:43

本文选题：毫米波 + AlGaN/GaN　；参考：《电子科技大学》2015年硕士论文

【摘要】：作为第三代半导体材料代表的GaN材料,相对来说具有禁带宽度大、击穿场强高以及高电子密度和高的电子迁移率等优点,因此成为高温、高频、微波毫米波领域半导体器件的理想材料。近年来,GaN基高电子迁移率晶体管(HEMTs)在高频大功率电路中的应用越来越得到人们的肯定并引起科研工作者和半导体公司的广泛研究。其中,AlGaN/GaN HEMT由于高的击穿电压和高的输出功率密度尤其受到青睐。目前,对微波频段的GaN HEMT物理模型和器件结构的研究已经很多,但毫米波段的研究报道还比较少。本文主要围绕毫米波段的AlGaN/GaN HEMT器件物理建模和场板技术展开研究,主要工作和创新点如下:首先,本文选择具有代表性的100nm栅长毫米波AlGaN/GaN HEMT器件作为研究对象,建立了完善的物理模型,该模型考虑了器件的表面态、陷阱和自热等效应,仿真得到的DC和RF特性曲线与器件实测结果吻合良好。利用该模型对器件的直流特性、频率特性、击穿特性和热特性等进行了仿真分析。其次,分析了器件物理结构参数变化对器件性能的影响,结果表明:栅源距离的增大会大幅降低器件的饱和输出电流;栅漏距离的增大可以提高器件的击穿电压,但同时也会造成器件截止频率的降低和膝电压的增大。最后,系统研究了场板技术在毫米波AlGaN/GaN HEMT器件中的应用,分析了栅场板结构、源场板结构和栅源双场板结构对器件击穿电压的提高作用,并对栅场板和源场板结构进行了优化设计。当场板长度为0.2μm,距离势垒层距离为40nm时可取得对势垒层电场的最佳调制效果,器件的击穿电压提高最多;三种结构得到的最大击穿电压分别为86V、74V和92V;采用栅源双场板结构对器件饱和输出功率密度的提高可高达38.5%,但双场板的使用也会严重恶化器件的频率特性。本文着重于使用TCAD工具来模拟毫米波GaN HEMT工作机制,预测器件性能,并对器件结构进行优化设计,对于毫米波GaN HEMT器件物理建模和结构优化具有指导意义。
[Abstract]:Gan, which is the representative of the third generation semiconductor materials, has the advantages of large band gap, high breakdown field strength, high electron density and high electron mobility, so it becomes high temperature and high frequency. Ideal material for semiconductor devices in the field of microwave and millimeter wave. In recent years, the application of GaN-based high electron mobility transistor (HEMTs) in high frequency and high power circuits has been more and more recognized and widely studied by researchers and semiconductor companies. AlGaN / gan HEMT is especially popular because of its high breakdown voltage and high output power density. At present, many researches have been done on the physical model and device structure of gan HEMT in microwave band, but there are few reports in millimeter band. This paper focuses on the physical modeling and field board technology of AlGaN / gan HEMT devices in millimeter band. The main work and innovations are as follows: firstly, the representative 100nm gate long millimeter wave AlGaN / gan HEMT devices are selected as the research object. A perfect physical model is established, which takes into account the surface state, trap and self-heating effects of the device. The DC and RF characteristic curves obtained by simulation agree well with the measured results. The DC, frequency, breakdown and thermal characteristics of the device are simulated and analyzed by using the model. Secondly, the effect of device physical structure parameters on the device performance is analyzed. The results show that the increase of gate source distance will greatly reduce the saturation output current of the device, and the increase of gate leakage distance can increase the breakdown voltage of the device. At the same time, the cutoff frequency of the device and the voltage of the knee will be increased. Finally, the application of field board technology in millimeter-wave AlGaN / gan HEMT devices is systematically studied. The effects of gate field plate structure, source field plate structure and gate dual field structure on the breakdown voltage are analyzed. The gate field plate and source field plate structure are optimized. When the length of the plate is 0.2 渭 m and the distance from the barrier layer is 40nm, the optimal modulation effect of the electric field of the barrier layer can be obtained, and the breakdown voltage of the device increases the most. The maximum breakdown voltages of the three structures are 86V, 74V and 92V, respectively. The output power density of the device can be increased up to 38.5 by using the gate source dual-field plate structure, but the frequency characteristics of the device will be seriously deteriorated by the use of the double-field plate. In this paper, TCAD tools are used to simulate the mechanism of millimeter wave gan HEMT, to predict the performance of the device, and to optimize the device structure, which is of great significance for the physical modeling and structural optimization of millimeter wave gan HEMT devices.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386

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