Self-assembled semiconductor quantum dots decorating the facets of GaAs nanowire for single-photon emission

In this chapter, we discuss the epitaxial growth of self-assembled quantum dots(QDs) in GaAs nanowires(NWs) and the characteristics of their single-photon emissions. We demonstrate Ga droplet-induced gold-free vapor-liquid-solid growth of hexagonal GaAs/Al GaAs core–shell NWs, branched GaAs NWs and tailored nanostructured morphologies on the NW facets. Particularly, we show two new types of QD-in-NW systems: one is a single InAs QD formed at the corner of a branched GaAs NW, and the other is a single GaAs QD formed on the NW facet. Sharp excitonic emission spectral lines are observed with vanishing two-photon emission probability. Furthermore, a single GaAs QD is achieved at the site of a single Al GaAs quantum ring(QR) on the NW facet. In addition, these NW-based single QDs are in-situ probed and integrated with single-mode optical ibers to achieve all-iber-output single-photon sources for potential application in quantum integrated networks.