Investigation and Mitigation of the Electrical Effects of Crystal Defects on SiC and GaN Devices

该项目将研究晶体缺陷对由碳化硅 (SiC) 和氮化镓 (GaN) 两种重要宽禁带半导体材料制成的 p-n 和肖特基二极管结的电性能的性能限制影响。 这些材料目前在高功率、高温、高频电子应用中都引起了极大的兴趣。 GaN 对于短波长光电应用也很感兴趣。 这些新材料的一个主要问题是晶体缺陷对击穿电压、漏电流和由它们制造的器件的其他非理想性的影响。 因此，我们的目标是系统地研究各种缺陷类别对每种材料中结点电性能的影响，以便能够识别并有针对性地消除最重要的缺陷。 将使用电流-电压和电容-电压测量、深能级瞬态光谱（DLTS）、电子束感应电流（EBIC）成像、正向和反向偏压下的电致发光以及热成像来研究缺陷。 晶体缺陷的性质将使用同步加速器白束 X 射线形貌术 (SWBXT)、光学显微镜和选择性蚀刻、扫描电子显微镜、原子力显微镜和透射电子显微镜 (TEM) 来确定。 将研究最多包含一种缺陷的非常小的设备，以隔离特定缺陷类型的影响。 还将研究几种钝化缺陷影响的方法。 计划与摩托罗拉和 Epitronics 进行工业合作。 博士学位学生将受到教育，有关宽间隙材料和设备的信息将通过互联网向其他大学和公众广泛提供。

This project will investigate the performance-limiting effects of crystal defects on the electrical properties of p-n and Schottky diode junctions made in two important wide-gap semiconductor materials, silicon carbide (SiC) and gallium nitride (GaN). These materials are both currently of great interest for high power, high temperature, high frequency electronic applications. GaN is also of interest for short wavelength optoelectronic applications. A major problem in these new materials is the effects of crystal defects on breakdown voltage, leakage currents, and other nonidealities of devices fabricated from them. The objective is therefore to systematically study the effects of various defect classes on electrical properties of junctions in each material, so that the most important defects can be identified and targeted for elimination. The defects will be studied using current-voltage and capacitance-voltage measurements, deep level transient spectroscopy (DLTS), electron beam induced current (EBIC) imaging, electroluminescence under forward and reverse bias, and thermal imaging. The nature of the crystalline defects will be determined using synchrotron white-beam X-ray topography (SWBXT), optical microscopy & selective etching, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy (TEM). Very small devices containing at most one defect will be studied to isolate the effects of specific defect types. Several methods of passivating the effects of defects will also be investigated. Industrial collaborations are planned with Motorola and Epitronics. A Ph.D. student will be educated, and information on wide gap materials and devices will be made widely available to other universities and the general public over the Internet.