Modification of coherent acoustic phonon lifetimes in thin gold films by self-assembled monolayers

MIKE HETTICH; AXEL BRUCHHAUSEN; OLIVER RISTOW; TOBIAS GELDHAUSER; DANIEL ISSENMANN; INGO WENKE; JÜRG BRYNER; JÜRG DUAL; THOMAS DEKORSY

Regensburg

Conferencia; Frühlingstagung – Deutsche Physikalische Gesellschaft (DPG-Spring-Meeting 2010); 2010

Deutsche Physicalisch Gesellschaft

The damping of coherent acoustic phonons in thin gold films has beeninvestigated by asynchronous optical sampling (ASOPS)[1].In order to measure the damping constants for various frequenciesgold films are grown in a wedge shape. Different film thicknesses correspondto changes in the phonon oscillation frequencies which cantherefore be measured by scanning over the sample surface.For lower frequency phonons in the range of 50 GHz to ∼ 75 GHza significant change in damping times is observed when a self assembledmonolayer is added between the gold film and the substrate. Thedamping behaviour with and without self-assembled monolayer hasbeen modelled with good agreement by a visco-elastic simulation.[1] A. Bartels et al., Rev. Sci. Instr. 78, 035107 (2007).