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

University Of Wisconsin-Eau Claire, Eau Claire WI

Investigators

Abstract

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. ***