Light impurities in/on crystalline solids give rise to localized vibrational modes, directly observed in infrared absorption. Using intense, time-resolved, infra-red radiation we have carried out direct measurements of the lifetime of a vibrationally excited state of an impurity in a solid. The lifetime, for hydrogen in silicon, is shown to vary over two orders of magnitude, (10psec-500psec), depending on the defect configuration of hydrogen within the silicon lattice. This lifetime determination is shown to be critical in describing a broad range of solid state-defect phenomena: 1) the longevity and lifetime of silicon (CMOS) transistors, 2) the understanding of intensity limitations in solid-state lasers, 3) the non-linear absorption properties required for (bio) materials modification with intense IR radiation, and 4) the interaction of defects with implanted ions. A very recent result employs this information in desorption of hydrogen from the silicon surface, and opens the possibility of surface-site selective desorption.
Co-workers: B. Sun and G. Lüpke, (William and Mary); N. H. Tolk, N. Rao, (Vanderbilt); Zhenyu Zhang, (ORNL); Zhiheng Liu, P.I. Cohen (Minn.)