Photoluminescence of tetrahedral quantum-dot quantum wells

TL;DR

This paper models the photoluminescence of tetrahedral quantum-dot quantum wells, revealing that shape influences exciton states and phonon interactions, with non-adiabatic theory explaining experimental phonon peak positions and Huang-Rhys parameters.

Contribution

It introduces a non-adiabatic approach considering tetrahedral shape effects to interpret photoluminescence spectra of QDQWs.

Findings

Exciton ground state is bright in tetrahedral QDQWs.

Phonon peaks are due to interface optical phonons.

Non-adiabatic theory accurately predicts Huang-Rhys parameter.

Abstract

Taking into account the tetrahedral shape of a quantum dot quantum well (QDQW) when describing excitonic states, phonon modes and the exciton-phonon interaction in the structure, we obtain within a non-adiabatic approach a quantitative interpretation of the photoluminescence spectrum of a single CdS/HgS/CdS QDQW. We find that the exciton ground state in a tetrahedral QDQW is bright, in contrast to the dark ground state for a spherical QDQW. The position of the phonon peaks in the photoluminescence spectrum is attributed to interface optical phonons. We also show that the experimental value of the Huang-Rhys parameter can be obtained only within the nonadiabatic theory of phonon-assisted transitions.