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arXiv · 2002.08172

Spatially-resolved luminescence and crystal structure of single core-shell nanowires measured in the as-grown geometry

Ali AlHassan·Jonas Lähnemann·Steven Leake·Hanno Küpers·Michael Niehle·Danial Bahrami·Florian Bertram·Ryan B. Lewis·Arman Davtyan·Tobias Schülli·Lutz Geelhaar·Ullrich Pietsch
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Abstract

We report on the direct correlation between the structural and optical properties of single, as-grown core-multi-shell GaAs/In$_{0.15}$Ga$_{0.85}$As/GaAs/AlAs/GaAs nanowires. Fabricated by molecular beam epitaxy on a pre-patterned Si(111) substrate, on a row of well separated nucleation sites, it was possible to access individual nanowires in the as-grown geometry. The polytype distribution along the growth axis of the nanowires was revealed by synchrotron-based nanoprobe X-ray diffraction techniques monitoring the axial 111 Bragg reflection. For the same nanowires, the spatially-resolved emission properties were obtained by cathodoluminescence hyperspectral linescans in a scanning electron microscope. Correlating both measurements, we reveal a blueshift of the shell quantum well emission energy combined with an increased emission intensity for segments exhibiting a mixed structure of alternating wurtzite and zincblende stacking compared with the pure crystal polytypes. The presence of this mixed structure was independently confirmed by cross-sectional transmission electron microscopy.

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Ali AlHassan, Jonas Lähnemann, Steven Leake, Hanno Küpers, Michael Niehle, Danial Bahrami, Florian Bertram, Ryan B. Lewis, Arman Davtyan, Tobias Schülli, Lutz Geelhaar, Ullrich Pietsch. 2020-02-19. Spatially-resolved luminescence and crystal structure of single core-shell nanowires measured in the as-grown geometry. https://doi.org/10.1088/1361-6528/ab7590

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