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

该项目针对高功率、高频器件应用的高阻碳化硅(SIC)中缺陷的结构和能级进行研究。对缺陷水平和相关缺陷结构的知识对于理解这种材料的优点和局限性是必不可少的。高电阻率的碳化硅是通过有意地引入本征缺陷来实现的，这些本征缺陷可以捕获由无意地并入的施主/受主杂质产生的自由载流子。最有效的陷阱是那些被大约一半的带隙能量电离的陷阱，因此它们的缺陷能级应该在导带边缘以下约1.6 eV。大多数用于测量缺陷级别的技术都是热法，对于大于1 eV的级别，需要高于500℃的温度。这里的方法将是利用光激励，以消除与高温下的电测量相关的困难。此外，还将使用电子顺磁共振(EPR)光谱，以便与缺陷能级同时确定缺陷的身份。光致EPR将被用来监测作为光子能量和/或时间的函数的特定缺陷光谱的强度，从而可以确定缺陷的类型、能级和弛豫能。结合光学导纳和光电流谱的结果，这些测量有望得到关于特定缺陷及其在碳化硅中的水平的更明确的图像。该项目将解决几种类型的半绝缘碳化硅中的缺陷及其水平，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片，以及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增长参数。*该项目致力于与电子和光子学具有很强技术相关性的基础材料研究，并将研究和教育结合在一起。学生们将学习基础物理和材料科学，同时在目前正在生产的高纯度半绝缘碳化硅基板上进行测量，以促进电子设备的新发展。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的学生，都将积极参与该项目。学生们将通过参加地方和国家会议以及参加旨在加强材料研究的课程来扩大他们的教育范围，如所提议的那样。该项目加强了UAB日益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。本实验的经验，以及与非UAB合作者一起成长为SIC的工作经验，将使PI和学生接触到广泛的学科，拓宽他们的研究范围。总体而言，该项目预计将为学生和半导体研究社区提供教育和技术方面的好处。

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.