Illumination-induced nonequilibrium charge states in self-assembled quantum dots

TL;DR

This paper investigates how constant illumination affects charge states in self-assembled InAs quantum dots, revealing nonequilibrium tunneling phenomena through capacitance-voltage spectroscopy and a new theoretical model.

Contribution

The study introduces a master-equation based model to explain nonequilibrium tunneling peaks observed in capacitance-voltage spectra of quantum dots under illumination.

Findings

Identification of additional nonequilibrium tunneling peaks

Model accurately predicts peak behavior under various conditions

Verification of the model with magnetic field experiments

Abstract

We report on capacitance-voltage spectroscopy of self-assembled InAs quantum dots under constant illumination. Besides the electronic and excitonic charging peaks in the spectrum reported earlier, we find additional resonances associated with nonequilibrium state tunneling unseen in C(V) measurements before. We derive a master-equation based model to assign the corresponding quantum state tunneling to the observed peaks. C(V) spectroscopy in a magnetic field is used to verify the model-assigned nonequilibrium peaks. The model is able to quantitatively address various experimental findings in C(V) spectroscopy of quantum dots such as the frequency and illumination dependent peak height, a thermal shift of the tunneling resonances and the occurrence of the additional nonequilibrium peaks.