Role of the Surface in the Electrical and Optical Properties of GaN and ZnO

技术上的。该项目研究了表面和界面在GaN和ZnO的电学和光学性质中所起的作用。它认为，表面相关效应可能是导致发射器效率降低、激光工作寿命缩短和电子器件提前退化的原因。此外，氧化锌的不可重复性和不稳定的p型导电性可能与该材料的表面导电性有关。本项目旨在对GaN和ZnO的表面及其附近的过程进行深入的研究。将在不同的环境条件、温度和光照下探测其电学和光学性质。我们将使用两种方法来研究表面附近的能带弯曲及其在光照(光电压)下的变化：1)开尔文探头与光学低温恒温器相结合；2)结合局部电荷注入和表面电荷随后成像的显微技术。表面带弯曲的潜在机制将与样品制备、温度和环境有关。还将探索有效的钝化方案，以提高基于这些宽带隙半导体的光学和电子器件的性能。该项目涉及具有技术相关性的电子/光子材料科学专题领域的基础研究问题。这一努力可能导致基于GaN和ZnO的更高可靠性、更长寿命和更高效率的明亮光源。拟议的研究计划将利用弗吉尼亚联邦大学(VCU)物理系和电气工程系的研究小组之间的密切合作，并启动与附近本科院校朗伍德大学化学和物理系的合作。该项目为VCU的研究生以及VCU和Longwood的本科生提供支持，所有学生都将参与多个研究小组之间的合作努力。将在这一项目中积极招募和支助妇女和任职人数不足的少数群体。弗吉尼亚州立大学是一所成长中的城市大学，学生群体多样化(18%是非洲裔美国人，22%是其他少数民族)，而皮耶罗？S有在实验室指导来自少数族裔的学生的记录。还计划与俄罗斯科学院约菲物理技术研究所开展一项国际合作。

Technical. This project addresses the role played by surfaces and interfaces in the electrical and optical properties of GaN and ZnO. It thought that surface-related effects may be responsible for reduced efficiency of emitters, shorter laser operation lifetimes, and earlier degradation of elec-tronic devices. Additionally, the irreproducible and unstable p-type conductivity of ZnO may be related to peculiarities of the surface conductivity in this material. This project aims for an in-depth investigation to gain a comprehensive understanding of the processes at and near the sur-face for both GaN and ZnO. Electrical and optical properties will be probed under different am-bient conditions, temperatures, and illumination. Band bending near the surface and its variation under illumination (photovoltage) will be studied using two methods: 1) a Kelvin probe com-bined with an optical cryostat; and 2) a microscopy technique combining local charge injection with subsequent imaging of the surface charge. The underlying mechanisms for surface band bending will be related to sample preparation, temperature, and ambient environment. Effective passivation schemes will also be explored to improve the performance of optical and electronic devices based on these wide-bandgap semiconductors.Non-Technical. The project addresses fundamental research issues in a topical area of elec-tronic/photonic materials science having technological relevance. This effort may lead to higher reliability, longer lifetime, and higher efficiency bright light sources based on GaN and ZnO. The proposed research program will leverage strong collaborations between research groups in the Departments of Physics and Electrical Engineering at Virginia Commonwealth University (VCU), as well as initiate a collaboration with the Department of Chemistry and Physics at Longwood University, a nearby undergraduate institution. The project provides support for graduate students at VCU and undergraduate students at both VCU and Longwood, where all of the students will be involved in collaborative efforts between multiple research groups. Women and underrepresented minority groups will be actively recruited and supported within this pro-ject. VCU is a growing urban university with a diverse student body (18% African American, 22% other minorities), and the PI?s have a record of mentoring students from underrepresented groups in their laboratories. An international collaboration is also planned with the Ioffe Physical Technical Institute of the Russian Academy of Science.