1. Nonlinear spectroscopy of planar and nano-crystalline silicon interfaces: experiments for ab initio theory Mike Downer, University of Texas at Austin, DMR-0207295 Modern nano-scale devices contain such thin films or small particles of silicon that unusual bonding structures at the interfaces can dominate device properties. For example, interfacial Si=O double bonds and oxygen vacancies cause Si nano-crystals to luminesce brightly, unlike bulk Si. Full understanding of such nano-interfaces requires noninvasive probes such as optical second-harmonic generation that can measure the spectrum of these otherwise inaccessible buried interfaces. Here we show second- harmonic light generated at Si nano- interfaces emerging in a double-lobed transverse mode, as predicted by our theoretical collaborators. Appl. Phys. Lett. 81, 3034 (2002) Phys. Rev. Lett. 94, 047401 (2005) TEM 01 mode of second-harmonic light generated at buried Si nano-interfaces TEM 00 mode of incident laser experimenttheory scanning electron micrograph of a single Si nanocrystal luminescence from Si nano-composite 3 nm

2. Education: Two REU undergraduates (Brian Mattern, James C. Miller) and four Ph.D. students (Ramon Carriles- Jaimes, Peter Figliozzi, Jinhee Kwon, Liangfeng Sun) are contributing to this work. Outreach: PI Mike Downer lectures to students in the “Lasers & Optics” class of Prof. Dhiraj K. Sardar, winner of the 2003 APS prize for research at an undergraduate institution, at nearby UT-San Antonio.* Nonlinear spectroscopy of planar and nano-crystalline silicon interfaces: experiments for ab initio theory Mike Downer, University of Texas at Austin, DMR-0207295 Graduate student Jinhee Kwon (left) with our theory collaborator Bernardo Mendoza (right) of Centro de Investi- gaciones en Optica (CIO), León, México at the 5th International Conference on Optics of Surfaces & Interfaces in León, May 2003. Graduate students Liangfeng Sun (left) and Ramon Carriles-Jaimes (right) October 2004 * More than 56 percent of UTSA's students come from groups underrepresented in higher education. UTSA ranks 4th in the nation in number of undergraduate degrees to Hispanics.

3. Nonlinear spectroscopy of planar and nano-crystalline silicon interfaces: experiments for ab initio theory Mike Downer, University of Texas at Austin, DMR-0207295 Technician displaying a 12” wafer at Sematech’s Austin, Texas facility. Industrial Liaison & Fund Leveraging: In summer 2004, the PI was awarded a grant by Austin-based Sematech to characterize silicon/high-K dielectric interfaces using the methods developed under this NSF project. Grant Title: “Spectroscopic Methods for Characterizing High-K dielectric films and Nanometer-Scale Silicon Channel Structures” Grant amount: $100K Sematech liaison: Alain C. Diebold* *editor of Handbook of Silicon Semiconductor Metrology (Marcel Dekker, 2001)