Type-II InAs/GaAsSb/GaAs quantum dots as artificial quantum dot molecules

TL;DR

This paper theoretically investigates type-II InAs/GaAsSb quantum dots, revealing their hole states resemble quantum dot molecules and exploring magnetic field tuning, with suggestions for enhancing tunability.

Contribution

It introduces a theoretical analysis of type-II InAs/GaAsSb quantum dots, highlighting their molecular-like hole states and proposing methods to improve magnetic tunability.

Findings

Hole states are segmented and resemble quantum dot molecules.

Singlet and triplet two-hole states with specific energy splittings.

Limited tunability range with magnetic field, with proposed enhancement approaches.

Abstract

We have studied theoretically the type-II GaAsSb capped InAs quantum dots for two structures differing in the composition of the capping layer, being either (i) constant or (ii) with Sb accumulation above the apex of the dot. We have found that the hole states are segmented and resemble the states in the quantum dot molecules. The two-hole states form singlet and triplet with the splitting energy of 4{\mu}eV / 325{\mu}eV for the case (i) / (ii). We have also tested the possibility to tune the splitting by vertically applied magnetic field. As the predicted tunability range was limited, we propose an approach for its enhancement.