Dynamics of Local Vibrational Modes in Semiconductors

College Of William And Mary, Williamsburg VA

Investigators

Abstract

Technical. This project addresses hydrogen defects in semiconductors, ferroelectrics, and insula-tors primarily through vibrational lifetime measurements. A major goal is to directly measure the vibrational energy transfer between two local vibrational modes of the same defect utilizing a two-color pump-probe transient bleaching approach. The project aims for a comprehensive study of vibrational lifetimes, microscopic dynamics and energy absorption in model crystalline semi-conductors and metal oxides. The focus is on wide band-gap and proton conducting oxides, in-cluding ZnO, MgO, SnO2, TiO2, BaTiO3, SrTiO3, and KTaO3. The ability to directly probe these pathways and rates allows tests of theory and scaling laws at new levels of precision. Dy-namical studies will provide new insight into the coupling of the ionic surroundings to the O-H vibration and the migration of protons within the oxide crystal lattice. The high-power tunable infrared radiation from the Free-Electron Laser at Jefferson Laboratory will be utilized to inves-tigate photo-induced H diffusion in proton conducting oxides. The proposed research is expected to lead to new fundamental understanding of basic energy transfer processes in electronic and photonic materials. Non-Technical. The project addresses fundamental research issues in a topical area of electronic and photonic materials science having technological relevance. The project integrates research and education providing graduate and undergraduate students with laboratory experience and training while conducting forefront research in an interdisciplinary field including modern optics, materials science and computational modeling.