Absorption and photoluminescence spectroscopy on a single self-assembled charge-tunable quantum dot

TL;DR

This study combines photoluminescence and absorption spectroscopy on a single charge-tunable quantum dot, revealing voltage-dependent exciton transitions and tunneling effects, with a Coulomb blockade model explaining the observations.

Contribution

It introduces a detailed model of Coulomb blockade effects in charge-tunable quantum dots and correlates PL and absorption spectra on the same single dot.

Findings

Neutral to charged exciton transition occurs at different voltages in PL and absorption.

Absorption broadens at large negative bias due to tunneling.

Resonant features appear when the hole level aligns with 2D hole states.

Abstract

We have performed detailed photoluminescence (PL) and absorption spectroscopy on the same single self-assembled quantum dot in a charge-tunable device. The transition from neutral to charged exciton in the PL occurs at a more negative voltage than the corresponding transition in absorption. We have developed a model of the Coulomb blockade to account for this observation. At large negative bias, the absorption broadens as a result of electron and hole tunneling. We observe resonant features in this regime whenever the quantum dot hole level is resonant with two-dimensional hole states located at the capping layer-blocking barrier interface in our structure.