  Quantum dots consisting of an axial Zn0.97Mg0.03Te insertion inside a large
bandgap Zn0.9Mg0.1Te nanowire cores are fabricated in a molecular beam epitaxy
system by employing the vapor-liquid-solid growth mechanism. Additionally, this
structure is coated with a thin ZnSe radial shell which forms type II interface
with the dot semiconductor. The resulting radial electron-hole separation is
evidenced by several distinct effects which occur in the presence of ZnSe
shell, including: the optical emission redshift of about 250 meV, a significant
decrease of the emission intensity, the increase of the excitonic lifetime by
one order of magnitude and the increase of the biexciton binding energy. The
type II nanowire quantum dots where electrons and holes are radially separated
constitute a promising platform for potential applications in the field of
quantum information technology.
