TED-AJ03-330 Thermophysical Property Measurements in Thin Films of Non-Noble Transition Metals

概要

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The Transient ThermoReflectance (TTR) technique has been demonstrated as a novel method for measuring transport properties in thin metallic films. The thermophysical properties of micro- and nanoscale structures have been shown to vary significantly from those of bulk materials due to both size effects and differences in the microscopic film structure. A pump-probe technique utilizing ultrashort laser pulses allows for the observation of thermal transport phenomena on a sub-picosecond time scale. This method relies on an intense heating beam to generate a transient thermal response in the thin metallic film. Focused at the center of the heated region, a lower intensity probe beam monitors the change in reflectance of the sample surface. Precise control of the probe path length produces a relative temporal delay between the pump and probe pulses. In non-noble transition metals (metals with at least one unoccupied d-orbital in the conduction band) the reflectance is linearly related to small changes in the electron and lattice temperatures. The transient data are compared to the Parabolic Two-Step (PTS) thermal diffusion model for measuring the electron-phonon coupling factor and thermal conductivity normal to the surface. Recent improvements in the data acquisition and data analysis software have noticeably enhanced this measurement technique. Experimental results for thin film platinum and nickel will be presented.