Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 54: Si/Ge

HL 54.3: Talk

Friday, February 29, 2008, 11:00–11:15, EW 202

Red-shift in SiNW Raman spectra - influence from thermal properties — •Sevak Khachadorian, Harald Scheel, and Christian Thomsen — Institute für Festkörperphysik, Technische Universität Berlin, 10623 Berlin, Germany

The Raman spectra of silicon nanowires are studied as a function of laser excitation power and temperature. With increasing temperature and laser excitation power we observe an amplification of the red-shift of the Raman frequency as well as of the broadening of the Raman peak. The Raman frequency varies linearly with the temperature. We observe a change of the slope in the frequency- excitation power diagram from a critical excitation power, which depends on the surrounding gas. From homogeneously heated experiments using a heating stage we find that the change of the slope in the frequency- excitation power diagram can be explained with inhomogeneous heating in the Raman volume generated by the Gaussian distribution of the intensity of the laser. With vacuum measurements we can rule out effects due to convection.