Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction"

In: MRS Proceedings, Jg. 1172 (2009), S. 4-8
ISSN: 1946-4274
Zeitschriftenaufsatz / Fach: Physik
Fakultät für Physik » Experimentalphysik
With time resolved ultrafast electron diffraction the cooling process across the interface between a thin film and the underlying substrate was studied after excitation with short laser pulses. From the exponential decay of the surface temperature evolution a thermal boundary conductance of 1430 W/(cm2K) is determined for a 9.7 nm thin Bi(111) film on Si(111). A linear dependence between laser fluence and initial temperature rise was measured for film-thicknesses between 2.5 nm and 34.5 nm. The ratio of initial temperature rise and laser fluence for different film-thicknesses is compared to a model taking multilayer optics into account. The data agree well with this model.