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HL: Fachverband Halbleiterphysik

HL 37: Quantum Dots and Wires: Optical Properties III

HL 37.7: Vortrag

Mittwoch, 24. März 2010, 11:15–11:30, H15

Single As-grown Al_xGa_1−xAs Nanowires Probed by Raman Spectroscopy — •Benjamin Buick¹, Eugen Speiser^1,2, Paola Prete³, Pasquale Paiano⁴, Nicola Lovergine⁴, and Wolfgang Richter¹ — ¹Università di Roma Tor Vergata, Rome, Italy — ²ISAS Department Berlin, Berlin, Germany — ³IMM-CNR di Lecce, Lecce, Italy — ⁴CNISM di Lecce and Università del Salento, Lecce, Italy

III-V compounds nanowires (NWs) are of central interest due to their innovative physical properties and potential applications in electronic and photo-electronic devices. Freestanding AlGaAs NWs were grown by MOVPE by the Vapor Liquid Solid method along the (111) direction on GaAs(111) substrates.

Raman measurements were performed on single as-grown NWs with a scanning confocal micro-Raman spectrometer. Rayleigh imaging, was applied to locate individual NWs and define their position for Raman measurements.

The spectra of the AlGaAs NWs exhibit two-mode behavior: GaAs- and AlAs-like modes which were exploited to determine the stoichiometry. Its dependence on the growth temperature was determined. The Raman spectra show two sets of GaAs- and AlAs-like modes indicating regions with different stoichiometries within a single NW. The composition gradient oft the NWs can be understood as the unintentional formation of a core-shell structure. Furthermore, the presence of coupled plasmon-LO phonon peaks in the spectra was related to (unintentional) doping of the NWs.