Inter-shell exchange interaction in CdTe/ZnTe quantum dots: magneto-photoluminescence of X, X2- and XX-

TL;DR

This study investigates exchange interactions in CdTe/ZnTe quantum dots through magneto-photoluminescence, revealing detailed fine structure of various excitonic states and quantifying exchange constants across many dots.

Contribution

It provides a comprehensive analysis of exchange interactions in CdTe/ZnTe quantum dots using magneto-photoluminescence, including the determination of effective exchange constants for multiple charge states.

Findings

Fine structure arises from electron-hole exchange interaction.

Spin Hamiltonians with effective exchange constants describe transitions in magnetic fields.

Exchange constants vary across quantum dots, with quantified values.

Abstract

We present a comprehensive photoluminescence study of exchange interaction in self-assembled CdTe/ZnTe quantum dots. We exploit the presence of multiple charge states in the photoluminescence spectra of single quantum dots to analyze simultaneously fine structure of different excitonic transitions, including recombination of neutral exciton/biexciton, doubly charged negative exciton and negatively charged biexciton. We demonstrate that the fine structure results from electron-hole exchange interaction and that spin Hamiltonians with effective exchange constants $\delta_i$ can provide a good description of each transition in magnetic field for Faraday and Voigt field geometry. We determine and discuss values of the effective exchange constants for a large statistics of quantum dots.