Materials World Network: A Novel Method for Study of Point Defects in Semiconductors Applied to Solar Cell Materials

技术总结在材料研究部的支持下，该项目包括合作研究和教育活动，将开发一种新的半导体表征技术--光调制光电子能谱，研究和创造对具有重要技术意义的半导体的新理解，并促进国际研究人员的交流。它的特点是具有互补技能的团队之间的协同合作，伊利诺伊大学厄巴纳香槟分校(UIUC)的罗基特和土耳其安卡拉比尔肯特大学的苏泽。比尔肯特小组最近对公认的X射线光电子能谱(XPS)技术进行了一项新的改进，将电荷灵敏度包括在内。UIUC集团拥有出色的整体材料分析能力和制造建议研究的材料的能力。这两个小组在不同的建模方法方面有互补的经验，并且以前一起发表过。罗基特集团将制造复杂的黄铜矿半导体，用于最先进的光伏技术，作为开发该技术的测试材料。两个小组都将对沉积材料进行测量，重点是技术上的增强，例如可以证明材料中电荷载流子动力学的时间相关性。元素敏感度和电荷敏感度将显示哪些缺陷负责捕获少数载流子，从而限制了器件的性能。该计划的教育部分侧重于在合作小组之间交流研究生和本科生，允许与国际学者互动，让学生有机会参加本国以外的会议，并在已经建立的初步合作的基础上，在两个参与研究小组和组织之间建立长期的研究关系。光电调制光电发射方法广泛适用于光电子学中的许多材料科学问题，并提供了一种独特的分析方法，可以获得基于现有技术无法获得的理解。非技术总结该项目将发展美国在土耳其安卡拉比尔肯特大学创造的一种分析光敏材料表面的新方法方面的专业知识。这项技术显示了当光线照射到材料上时，哪些原子会带电，这有助于理解如何从材料中获取能量，比如在太阳能电池中，以及是什么限制了材料的性能。这项研究的结果将增进对发光(如固态照明)和光吸收(如太阳能电池)技术的理解和开发，这些技术已被确定为对美国长期能源独立至关重要。该计划的更广泛影响包括分析技术的适用性，这将促进美国许多涉及光发射或吸收设备的技术的发展。该项目将加强美国和土耳其的互动和跨文化理解。通过研究生和本科生的双向交流，美国未来的技术领导者将熟悉重要的世界文化和中东发展中的经济强国。该项目将吸收妇女作为研究生，以促进科学/工程领域的性别平等(“STEM”)。这项研究将支持美国新兴产业的几项新型太阳能电池技术的开发。这可能会导致一个主要的太阳能电池行业的增长，并创造大量的就业机会。与此同时，根据该计划培训的科学家和工程师将为这些公司提供熟练的员工，这将促进美国工业的增长。

TECHNICAL SUMMARYWith support from the Division of Materials Research, this project consists of collaborative research and educational activities that will develop a novel semiconductor characterization technique, photomodulated photoelectron spectroscopy, study and create new understanding of technologically important semiconductors, and foster international exchange of researchers. It features a synergistic collaboration between the groups with complementary skills, Rockett at the University of Illinois at Urbana Champaign (UIUC), and Suzer at Bilkent University, Ankara, Turkey. The Bilkent group has recently introduced a novel enhancement to the well-established technique of X-ray Photoelectron Spectroscopy (XPS), to include charge sensitivity. The UIUC group has excellent overall materials analytical capability and the ability to fabricate the materials proposed for study. Both groups have complementary experience with various methods of modeling and have published together previously. The Rockett group will fabricate complex chalcopyrite semiconductors used in state-of-the-art photovoltaics as test materials for development of the technique. Both groups will conduct measurements of the deposited materials focusing on enhancements in the techniques such as time dependence that can demonstrate charge carrier dynamics in the materials. Elemental sensitivity coupled with charge sensitivity will show which defects are responsible for trapping of minority carriers, which limits device performances. The educational component of the program focuses on exchange of graduate and undergraduate students among the collaborating groups, allowing interaction with international scholars, and giving students the opportunity to attend conferences outside of their home country, and establishing a long-term research relationship between the two participating research groups and organizations, based on a preliminary collaboration already in place. The photomodulated photoemission method is broadly applicable to many materials science problems in optoelectronics and provides a unique analytical method that yields understanding not accessible based on existing techniques.NON-TECHNICAL SUMMARYThis project will develop US expertise in a new method of analyzing the surface of light-sensitive materials created at the Bilkent University in Ankara, Turkey. This technique shows which atoms are becoming charged when light strikes the material, which helps to understand how energy can be harvested from the material, as in a solar cell, and what limits that material's performance. The results of the research will enhance understanding and development of both light emitting (as in solid state lighting) and light absorbing (as in solar cells) technologies that have been identified as crucial to the long-term energy independence of the US. The broader impacts of the program include the applicability of the analytical technique, which will enhance the development of many technologies in the US involving light emission or absorption devices. The project will enhance US-Turkish interactions and intercultural understanding. Through bidirectional exchange of both graduate and undergraduate students, future technical leaders in the US will become familiar with an important world culture and a developing economic power in the Middle East. The project will incorporate women as graduate students to promote gender equity in science/engineering ("STEM"). The research will support the development of several novel solar cell technologies with nascent industries in the US. This can lead to the growth of a major solar cell industry and significant job creation. At the same time the scientists and engineers trained under the program will provide skilled employees to these companies that will foster growth of US industry.