Quantum confinement in optically active ultrathin (Cd,Mn)Te/(Cd,Mg)Te core/shell nanowires

The fabrication of ultrathin (Cd,Mn)Te nanowires with diameters reaching values below 10 nm is reported. The thinning procedure relies on a thermally induced reverse reaction process applied to (Cd,Mn)Te nanowires grown using the vapor-liquid-solid method. The impact of quantum confinement is manifested by a distinct blueshift of the excitonic emission from individual nanowires. Cathodoluminescence mapping reveals that the optical emission originates from relatively short nanowire segments, which is explained in terms of exciton localization on irregularities of nanowire core diameter. Magneto-optical study performed on several individual nanowires reveals a change from light hole to heavy hole character of the excitonic emission depending on the emission energy, i.e., on the size of the emitting object. The results are interpreted in terms of the influence of axial and radial quantum confinement on excitons in ultrathin nanowires.