We present a combined photoluminescence and transmission electron microscopy study of single GaAs nanowires. Each wire was characterized both in microscopy and spectroscopy, allowing a direct correlation of the optical and the structural properties. By tuning the growth parameters, the nanowire crystal structure is optimized from a highly mixed zincblende–wurtzite structure to pure wurtzite. We find the latter one to be stacking-fault-free over nanowire lengths up to 4.1 μm. We observe the emission of purely wurtzite nanowires to occur only with polarization directions perpendicular to the wurtzite -axis, as expected from the hexagonal unit cell symmetry. The free exciton recombination energy in the wurtzite structure is 1.518 eV at 5 K with a narrow linewidth of 4 meV. Most notably, these pure wurtzite nanowires display long carrier recombination lifetimes of up to 11.2 ns, exceeding reported lifetimes in bulk GaAs and state-of-the-art 2D GaAs/AlGaAs heterostructures.
Long exciton lifetimes in stacking-fault-free wurtzite GaAs nanowires
Stephan Furthmeier, Florian Dirnberger, Joachim Hubmann, Benedikt Bauer, Tobias Korn, Christian Schüller, Josef Zweck, Elisabeth Reiger, Dominique Bougeard; Long exciton lifetimes in stacking-fault-free wurtzite GaAs nanowires. Appl. Phys. Lett. 1 December 2014; 105 (22): 222109. https://doi.org/10.1063/1.4903482
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