Carrier confinement and bond softening in photoexcited bismuth films

Taeho Shin, Johanna W. Wolfson, Samuel W. Teitelbaum, Maria Kandyla, Keith A. Nelson

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Femtosecond pump-probe spectroscopy of bismuth thin films has revealed strong dependencies of reflectivity and phonon frequency on film thickness in the range of 25-40nm. The reflectivity variations are ascribed to distinct electronic structures originating from strongly varying electronic temperatures and proximity of the film thickness to the optical penetration depth of visible light. The phonon frequency is redshifted by an amount that increases with decreasing film thickness under the same excitation fluence, indicating carrier density-dependent bond softening that increases due to suppressed diffusion of carriers away from the photoexcited region in thin films. The results have significant implications for nonthermal melting of bismuth as well as lattice heating due to inelastic electron-phonon scattering.

Original languageEnglish (US)
Article number184302
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume92
Issue number18
DOIs
StatePublished - Nov 10 2015

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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