RUI: The Interdependence of GaN Surface Chemistry and Surface Morphology and Reconstruction

这个RUI项目研究GaN表面的化学性质，以及这些反应如何受到表面形态（簇覆盖或光滑）的影响，以及相反，表面形态如何被反应改变。GaN上的团簇形成似乎特别容易，与原子光滑表面相比，预计会产生富含ga的表面。表面反应，提前簇的形成以及蚀刻反应将是提出的研究重点。表面反应将通过使用紫外光电子能谱和通过确定分子从表面解吸的温度来监测表面电子结构的变化。表面形貌将用扫描隧道显微镜和低能电子衍射来表征。实验将通过在表面反应之前制备具有已知形貌的表面来确定表面形貌如何影响化学。表面化学如何改变形貌将通过在表面反应后重新检查GaN表面来评估局部表面结构或组成如何变化来表征。成分和电子密度的变化也将通过紫外线和x射线光电子能谱来评估。通过比较表面与已知的形态变化，光电子能谱可以确定表面是光滑的还是簇覆盖的。该项目涉及具有技术相关性的材料科学主题领域的基础研究问题。本科生将在该项目中发挥主要作用，有机会直接将研究整合到他们的学术课程中。威斯康星大学欧克莱尔分校化学和物理学院之间新建立的合作加强了该项目。最近通过NSF MRI奖获得的仪器设备已合并为一个通用材料研究设施，来自几个小组和部门的教师和学生作为一个团队在各种研究项目上工作。这种跨学科的材料研究方法为本科生提供了一个与同龄人直接合作的环境，并培养了合作学习技能，同时也指导了经验不足的学生。该研究项目为本科生提供了最前沿的研究和最先进的表面科学设备。＊＊＊

This RUI project addresses the chemistry of GaN surfaces and how these reactions are influenced by surface morphology (cluster-covered or smooth), and conversely how surface morphology is modified by reactions. Cluster formation on GaN appears to be especially facile, and is expected to result in Ga-rich surfaces compared to atomically smooth surfaces. Surface reactions that pres-age cluster formation as well as etching reactions will be the focus of the proposed research. Sur-face reactions will be monitored by changes in surface electronic structure using ultraviolet pho-toelectron spectroscopy and by determining the temperature at which molecules desorb from the surface. Surface morphology will be characterized using scanning tunneling microscopy and low-energy electron diffraction. Experiments will determine how surface morphology influences chemistry by preparing a surface with known morphology before surface reactions. How surface chemistry changes morphology will be characterized by re-examining the GaN surface after sur-face reactions to assess how local surface structure or composition has changed. Changes in composition and electron density will also be evaluated by ultraviolet and X-ray photoelectron spectroscopy. By comparing surfaces with known changes in morphology, it may be possible to establish whether a surface is smooth or cluster-covered by photoelectron spectroscopy.%%% The project addresses fundamental research issues in a topical area of materials science having technological relevance. Undergraduate students will play a primary role in the project, with op-portunities for research integrated directly into their academic program. A newly established collaboration between UW-Eau Claire chemistry and physics faculty enhances the project. In-strumentation recently acquired through NSF MRI awards has been combined into a common-use materials research facility in which faculty and students from several groups and departments work as a team on various research projects. This interdisciplinary approach to materials research provides an environment where undergraduate students work directly with their peers, and de-velop cooperative learning skills as well as mentoring less-experienced students. The research program enables forefront research and access to state-of-the-art surface science equipment to undergraduate students. ***