Piezoelectric exciton-acoustic phonon coupling in single quantum dots

TL;DR

This study investigates exciton-acoustic phonon interactions in single InAs/AlAs quantum dots, revealing piezoelectric coupling effects and their dependence on excitation conditions through detailed micro-photoluminescence spectroscopy.

Contribution

It provides the first detailed experimental evidence of exciton-acoustic phonon piezoelectric coupling in single quantum dots and explores how excitation conditions influence this interaction.

Findings

Identification of narrow low-energy sidebands due to piezoelectric coupling

Observation of the dominance of sidebands at lower excitation energies and intensities

Screening of piezoelectric coupling at high excitation intensities

Abstract

Micro-photoluminescence spectroscopy at variable temperature, excitation intensity and energy was performed on a single InAs/AlAs self-assembled quantum dot. The exciton emission line (zero-phonon line, ZPL) exhibits a broad sideband due to exciton-acoustic phonon coupling by the deformation potential mechanism. Additionally, narrow low-energy sidebands at about 0.25 meV of the ZPL are attributed to exciton-acoustic phonon piezoelectric coupling. In lowering the excitation energy or intensity these bands gradually dominate the emission spectrum of the quantum dot while the ZPL disappears. At high excitation intensity the sidebands due to piezoelectric coupling decrease strongly and the ZPL dominates the spectrum as a consequence of screening of the piezoelectric coupling by the photocreated free carriers.