Peculiar spectra of dark and bright excitons in alloyed nanowire quantum dots

TL;DR

This paper investigates the unique spectral properties of excitons in alloyed nanowire quantum dots, revealing alloying-induced bright exciton splitting and tunability, with implications for quantum optoelectronic applications.

Contribution

It demonstrates that alloying alone causes significant bright exciton splitting and shows how electric fields can tune this effect, challenging previous theoretical assumptions.

Findings

Alloying causes bright exciton splitting over 15 μeV.

Electric fields can tune the splitting below 1 μeV.

Dark excitons exhibit strong alloying effects with large out-of-plane polarization.

Abstract

Excitons in alloyed nanowire quantum dots have unique spectra as shown here using atomistic calculations. The bright exciton splitting is triggered solely by alloying and despite cylindrical quantum dot shape reaches over $15~\mu$eV, contrary to previous theoretical predictions, however, in line with experimental data. This splitting can however be tuned by electric field to go below $1$~$\mu$eV threshold. The dark exciton optical activity is also strongly affected by alloying reaching notable $1/3500$ fraction of the bright exciton and having large out-of-plane polarized component.