Detection of the Structure and Electrical Level of Defects in Semi-Insulating SiC

该项目解决了高电阻率碳化硅（SiC）的结构和能级缺陷，用于高功率，高频器件应用。了解缺陷等级和相关的缺陷结构对于理解这种材料的优点和局限性是必不可少的。高电阻SiC是通过有意地加入固有缺陷来实现的，这些缺陷可以捕获由无意加入的供体/受体杂质产生的自由载流子。最有效的陷阱是那些被约一半带隙能量电离的陷阱，因此它们的缺陷能级应低于导带边缘~1.6 eV。大多数用于测量缺陷水平的技术都是热方法，对于大于1ev的水平，需要高于500C的温度。这里的方法是利用光激发，以消除在高温下与电测量相关的困难。此外，将采用电子顺磁共振（EPR）光谱，以便在确定缺陷水平的同时确定缺陷的身份。光诱导EPR将用于监测特定缺陷光谱的强度作为光子能量和/或时间的函数，以便确定缺陷的类型，其水平和弛豫能。结合光学导纳和光电流光谱的结果，这些测量结果有望产生更明确的特定缺陷及其在SiC中的水平。该项目将解决几种类型的半绝缘SiC的缺陷及其水平，包括通过物理气相沉积和高温化学气相沉积生长的商业晶圆，以及由大学同事生长的高纯度CVD外延层。反过来，这些研究将有助于建立更好的生长参数。***该项目致力于与电子和光子学技术密切相关的基础材料研究，并将研究与教育相结合。学生将学习基础物理和材料科学，同时对目前生产的高纯度半绝缘碳化硅衬底进行测量，以促进电子设备的新发展。从大学预科到研究生阶段的学生，无论是在UAB内部还是从附近的高中和大学招募，都将积极参与该项目。学生们将通过参加地方和国家会议和参加旨在增加这些提议的材料学习的课程来扩大他们的教育。该项目加强了UAB不断增长的材料科学工作，并支持目前建立UAB材料研究实验室的活动。在这个实验室的经验，以及与非uab合作伙伴一起种植碳化硅的经验，将使PI和学生接触到广泛的学科，扩大他们的研究范围。总体而言，该项目有望为学生和半导体研究界提供教育和技术效益。

This project addresses the structure and energy level of defects in high resistivity silicon carbide (SiC) considered for high power, high frequency device applications. Knowledge of defect levels and associated defect structure is essential for understanding the benefits and limitations of this material. High resistivity SiC is achieved by intentionally incorporating intrinsic defects that can trap free carriers generated by unintentionally incorporated donor/acceptor impurities. The most effective traps are those that are ionized by energies of about half the band gap, so that their defect level should be ~1.6 eV below the conduction band edge. Most techniques designed to measure defect levels are thermal methods, which for levels greater than 1 eV require temperatures greater than 500C. The approach here will be to utilize optical excitation in order to eliminate difficulties associated with electrical measurements at high temperature. Furthermore, electron paramagnetic resonance (EPR) spectroscopy will be employed so that the identity of the defects will be determined simultaneously with the defect level. Photo-induced EPR will be used to monitor the intensity of specific defect spectra as a function of photon energy and/or time so that the type of defect, its level, and the relaxation energy can be determined. Combined with results for optical admittance and photocurrent spectroscopies, these measurements are expected to yield a more definitive picture of specific defects and their levels in SiC. The project will address the defects and their level in several types of semi-insulating SiC including commercial wafers grown by physical vapor deposition and high temperature chemical vapor deposition as well high purity CVD epitaxial layers grown by university colleagues. In turn, these studies will be beneficial to help establish improved growth parameters. *** The project addresses fundamental materials research with strong technological relevance to electronics and photonics, and integrates research and education. Students will be learning fundamental physics and materials science while making measurements on high purity semi-insulating silicon carbide substrates presently being produced to facilitate a new thrust in electronic devices. Students at the pre-college through graduate levels, both within UAB and recruited from nearby high schools and universities, will be actively involved in the project. Students will broaden their education by participating at local and national meetings and attending classes designed to augment materials studies like those proposed. The project enhances the growing materials science effort at UAB and supports current activities to establish a UAB materials research laboratory. Experience in this lab, along with that gained working with non-UAB collaborators who grow SiC, will expose the PI and students to a broad range of disciplines widening their research scope. Overall, the project is expected to provide educational and technological benefits to the students and the semiconductor research community.