Ultrafast electron and phonon response of oriented and diameter-controlled germanium nanowire arrays.

Li, Yanying; Clady, Raphael; Park, Junghyun; Thombare, Shruti V; Schmidt, Timothy W; Brongersma, Mark L; McIntyre, Paul C · Nano Lett · 2014

basic_science · Level V

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Abstract

Carrier and phonon dynamics in dense arrays of aligned, single-crystal Ge nanowires (NWs) of controlled diameter are investigated by ultrafast optical pump-probe measurements, effective medium calculations, and elasticity analysis. Both a pronounced induced absorption and the amplitude and spectral range of Fabry-Perot oscillations observed in the probe signal are predicted for the NW array/air metamaterial by effective medium calculations. Detected temporal oscillations of reflectivity are consistent with excitation of radial breathing mode acoustic phonons by the intense pump pulse.