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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.64: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Resonant Raman Profiles in GaAs and AlGaAs Nanowires at the Bandgap — •Oliver Schimek¹, Megan Brewster², Silvija Gradecak², and Stephanie Reich¹ — ¹Fachbereich Physik, Freie Universität, Berlin — ²Massachusetts Institute of Technology, Cambridge

The properties of low dimensional systems like nanowires hold promise for novel electronic devices like nanowire-based transistors, sensors and single photon sources. Here we are investigating the physical properties like electron-phonon coupling by means of Raman spectroscopy. We present resonance data of GaAs and AlGaAs nanowires at the bandgap energy. The photoluminescence is effectively quenched in nanowires and therefore the bandgap can directly be probed. Such nanowires show an unexpectedly strong second order LO phonon such that the ratio 2LO:1LO reaches values up to 6 under resonant conditions. We also present a model of two phonon resonant Raman scattering via excitons. This model explains the observed 2LO resonance profile. The resonance data of the AlGaAs nanowires show a dip in the 1LO curve at the position of the 2LO maximum which suggests that the 2LO intensity occurs at expense of the 1LO intensity. Additionally, we present data of Si doped GaAs nanowires whose increased concentration of free carriers results in a interference known as the Fano effect.