Carrier separation in type II quantum dots inserted in (Zn,Mg)Te/ZnSe nanowire
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.