Roughening, Etching, and Nanoscale Patterning of Si and Ge

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This project focuses on atomic-scale interactions associated with thermally-activated dry etching, and with surface roughening without etching (desorption). Silicon (100) surfaces with adsorbed halogens serve as model systems to address problems of broad interest including how and why surface modifications occur when there are competitive reaction pathways and how adsorbates and strain alter the energetics of reaction. Comparison to results for germanium (100) will test the generality of conclusions drawn for silicon (100). The emphasis is on structural changes at surfaces. Variable temperature scanning tunneling microscopy is used to advance the understanding of roughening, etching, and nanoscale patterning to a new level by following modifications as they occur, event-by-event, at high temperature.%%%A key component of the proposed program involves the education and training of graduate and undergraduate students. Students supported by the NSF would join a group made up of people from around the world. They would work with senior group members while they become familiar with the laboratory. In general, students are coauthors of publications by the end of the second year. They participate fully in the preparation of manuscripts, both their own and those of other group members, and of proposals such as this one. They are expected to compete for student prizes, to present papers at conferences. They are also expected to contribute to the education of younger students. Undergraduate students are fully integrated into the group, and their contributions are reflected by coauthorship of publications. Our laboratories are open for visits by prospective undergraduate and graduate students, freshmen involved in Engineering Open House and upperclassmen involved in senior design projects benefit from access to them. Twenty-six percent of the graduate students in Materials Science at UIUC are women; a goal is to increase the overall number and to recruit into the Weaver group. Instrumentation will be developed for variable temperature scanning tunneling microscopy, a state of the art technique. Collaborative projects are encouraged. The results will be disseminated through publications, contributed conference papers, and invited talks and seminars, as in the past with results obtained under NSF support. While there is a rich literature that describes atomic-scale growth of films and nanostructures, frequently with key insights provided by scanning tunneling microscopy, far much less attention paid to material removal and the prospects of nanoscale patterning. Our focus on material removal provides important insights that will broaden the knowledge base significantly and will contribute to advanced technologies.