Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 72: Quantum wires

HL 72.3: Talk

Thursday, March 19, 2015, 10:45–11:00, EW 203

Optical properties of ultrathin GaAs-AlGaAs core-shell nanowires — •Julia Winnerl¹, Bernhard Loitsch¹, Daniel Rudolph¹, Stefanie Morkötter¹, Gianluca Grimaldi¹, Lukas Hanschke¹, Lucas Schweickert¹, Max Bichler¹, Gerhard Abstreiter^{1, 2}, Jonathan Finley¹, and Gregor Koblmüller¹ — ¹Walter Schottky Institut and Physik Department, Technische Universität München, Garching, Germany — ²Institute for Advanced Study, Technische Universität München, Garching, Germany

III-V semiconductor nanowires (NWs) are known to provide a large field for many applications in electronic and optoelectronic devices. In many of these NW device applications, the electronic properties of the NWs are mostly described by the 3D bulk-like properties of the NW core, in spite of the 1D-like structure of the NWs. Performance enhancements in such NW device applications are expected from exploiting 1D-quantum confinement effects. Here, we present the optical properties of GaAs-Al_0.3Ga_0.7As core-shell NWs epitaxially grown on silicon with GaAs core diameters below 10 nm. Low-temperature micro-photoluminescence (PL) measurements reveal strongly blue-shifted PL energies (up to ∼100 meV) compared to the free exciton emission of GaAs. This indicates strong radial 1D-quantum confinement of the GaAs NW core. In addition, the strongly blue-shifted PL shows some sharp PL lines indicating that additional axial confinement effects of the excitons are present. Time-resolved PL experiments show clear bi-exponential decay transients that could be attributed to different recombination channels of these localized excitons.