Tunable GaAsxP1x Quantum-Dot Emission in Wurtzite GaP Nanowires

We present a fairly understudied material system suitable for the realization of tunable quantum dot (QD) emission within the visible-to-near-infrared spectrum (in particular, in the 650-720 nm wavelength range). Specifically, crystal-pure wurtzite (WZ) Gallium Phosphide (GaP) nanowires (NWs) are synthesized, incorporating single Gallium Arsenide Phosphide (GaAsxP1-x) QDs of various compositions. Detailed growth procedures are outlined, accompanied by the analysis of the synthesis challenges encountered during the realization of these nanostructures and the strategies to solve them. Notably, a great degree of control over the shape and the composition of the ternary alloy QD is achieved, enabling a well-defined confinement and the tunability of the emission wavelength. This is confirmed by low temperature micro-photoluminescence (μ-PL) investigation showing that the NW emission is dominated by a narrow peak whose energy shifts according to the As content of the QD: from ~ 650 nm (As = 70%) to ~ 720 nm (As = 90%). Moreover, a localized and efficient carrier recombination mechanism is found by single-NW μ-PL mapping, confirming that this emission arises from the QD. Finally, a power and temperature μ-PL study is presented and used to characterize the QD excitonic properties and the nature of the involved energy levels. Our findings underscore the potential for these QDs in NWs with tailored composition to achieve the desired light emission characteristics, thereby advancing applications in quantum optics and nanophotonics.