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

TL;DR

This paper reports the fabrication of type II quantum dots within nanowires, demonstrating significant electron-hole separation effects that enhance their potential for quantum information applications.

Contribution

It introduces a novel type II quantum dot structure in nanowires with detailed fabrication and characterization, highlighting their unique optical and electronic properties.

Findings

Redshift of optical emission by 250 meV

Increase in excitonic lifetime by tenfold

Enhanced biexciton binding energy

Abstract

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.