Experimentally measured pile-up of isotopic oxygen

1. Nanoscale Foreign-Atom Pile-up Near Semiconducting Oxide Surfaces is QuantifiedEdmund G. Seebauer, Univ of Illinois at Urbana-Champaign, DMR 1005720 • Goal: To control concentration and movement of defects in semiconducting ceramics using surfaces • Outcome:Foreign-atom pile-up has been quantified and modeled near the surfaces of several semiconductors including oxides of titanium and zinc • Impact: May improve the performance of devices for producing hydrogen fuel from sunlight, photo-catalysts for wastewater cleanup, gas sensors • Summary: Electric charge that typically resides on a ceramic surface or interface can interact with electrically-charged extra atoms (defects known as “interstitial atoms”) in the underlying bulk. Prof. Edmund G. Seebauer and his graduate students have quantified experimentally how this interaction causes foreign atoms such as isotopically labeled oxygen to pile-up within the first few nanometers of the surface in zinc oxide and titanium dioxide. Through mathematical simulation, these workers have also shown how the amount of pile-up depends upon both the amount of electric charge at the surface and the native ability of the surface to absorb interstitial atoms. Both these attributes of the surface can be controlled to some extent. Thus, the modeling shows the way to manipulate the pile-up to optimize, for example the electrical resistance and capacitance at a metal contact with a ceramic-based gas sensor. TiO2 Experimentally measured pile-up of isotopic oxygen near the surface of zinc oxideand titanium dioxide Simulated variation of the boron pile-up (P) with an Si-SiO2 interface’s electric charge (V) and interstitial atom absorbing power (S). No pile-up for large S, small V.

2. Promoting “Virtue Ethics” in STEM DisciplinesEdmund G. Seebauer, Univ of Illinois at Urbana-Champaign, DMR 1005720 • Background: Imparting a sense of research ethics represents an important and sometimes difficult task for a graduate advisor. • Recent activities: • Maintenance of ethics Web site www.scs.uiuc.edu/ethics/ • Written articles (e.g., recently-completed chapter on virtue ethics in Practical Ethics for Food Professionals, ed. Clark & Ritson, Wiley-Blackwell publ.)