Abstract
Embedding quantum dots in nanowires (NWs) constitutes one promising building block for quantum photonic technologies. Earlier attempts to grow InAs quantum dots on GaAs nanowires were based on the Stranski–Krastanov growth mechanism. Here, we propose a novel strain-driven mechanism to form 3D In-rich clusters on the NW sidewalls and also on the NW top facets. The focus is on ternary InGaAs nanowire quantum dots which are particularly attractive for producing single photons at telecommunication wavelengths. In(Ga)As clusters were realized on the inclined top facets and also on the {11-2} corner facets of GaAs NW arrays by depositing InAs at a high growth temperature (630 °C). High-angle annular dark-field scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy confirms that the observed 3D clusters are indeed In-rich. The optical functionality of the as-grown samples was verified using optical technique of cathodoluminescence. Emission maps close to the NW tip shows the presence of optically active emission centers along the NW sidewalls. Our work illustrates how facets can be used to engineer the growth of localized emitters in semiconducting NWs.
Highlights
Single photon emitters (SPEs) are envisioned to play a central role in the future of quantum photonics
Recent in-situ transmission electron microscopy (TEM) growth experiments have shown that ZB phase is favoured at small (125◦) contact angles while WZ phase is favoured at any intermediate contact angle [22]
We have studied the effect of NW growth termination on the morphology of the GaAs NW tips obtained in ordered arrays
Summary
Single photon emitters (SPEs) are envisioned to play a central role in the future of quantum photonics. Bright single-photon emitters have been demonstrated by embedding semiconducting quantum dots (QDs) within nanowires (NWs) [3,4,5,6]. Apart from efficient light extraction, the size and morphology of the NWs offer several degrees of freedom to form low dimensional heterostructures like QDs and quantum wells (QWs). NWs provide a wider choice of material combinations with a higher lattice mismatch for forming axial and radial heterostructures. In the case of III–V semiconductors, axial heterostructures are obtained by either changing the group-III element, like GaAs/InAs, GaP/InP, or the group-V element like GaAs/GaSb. More combinations are available if either A or B is a ternary alloy. The Ga droplet, used as a growth catalyst, is completely consumed before the deposition of InAs. Formation of axial and radial localized InGaAs clusters within self-catalysed GaAs NWs is observed.
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