Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 72: Quantum wires

HL 72.4: Vortrag

Donnerstag, 19. März 2015, 11:00–11:15, EW 203

Photoluminescence excitation measurements on ultrathin GaAs-AlGaAs core-shell nanowires — •Gianluca Grimaldi, Bernhard Loitsch, Daniel Rudolph, Stefanie Morkötter, Lukas Hanschke, Lucas Schweickert, Max Bichler, Gerhard Abstreiter, Jonathan Finley, and Gregor Koblmüller — Walter Schottky Institut, Technische Universität München, Garching, Germany

Thin semiconductor nanowires (NWs) can achieve quantum confinement of carriers in the radial direction, potentially enhancing performances of NW-based devices. Using a novel reverse-reaction growth scheme, GaAs-AlGaAs core-shell NWs with tunable core diameters down to below 10 nm can be epitaxially integrated on silicon [1].

Here we report on micro-photoluminescence spectroscopy (μ-PL) and photoluminescence excitation spectroscopy (PLE) on GaAs-AlGaAs core-shell NWs with ultrathin core diameters (7-20 nm). Along with the blueshift of PL, arising from radial confinement in the thin NW core, multiple sharp peaks are observed, with FWHM below 100 μeV. Power-dependent PL reveal saturation of these peaks for high excitation power, further suggesting presence of localized exciton states. PLE experiments show resonances, whose energy distance is smaller than what expected for excited states of the radial confinement, suggesting that additional confinement in the axial direction is present. The axial localization is attributed to the presence of wurtzite and zincblende stacking along the NWs.

Reference: [1] B. Loitsch, et al., in review (2014)