Two-way photoeffect-like occupancy dynamics in a single (InGa)As quantum dot

TL;DR

This study investigates the complex spin and charge dynamics in single (InGa)As quantum dots under high magnetic fields, revealing a photoeffect mechanism that influences occupancy and charge recharging processes.

Contribution

It introduces an extended theoretical framework and experimental analysis showing that high magnetic fields induce a photoeffect that affects quantum dot occupancy, beyond traditional Auger-recombination explanations.

Findings

Kerr fluctuations exhibit richer spectral features at high magnetic fields.

Photoeffect, not Auger-recombination, dominates charge dynamics at high fields.

Recharging involves acceptor-bound holes activated by the probe laser.

Abstract

We extend optical spin noise spectroscopy on single (InGa)As quantum dots to high magnetic fields at which the splitting between the two optical active Zeeman branches of the positively charged quantum dot trion transition is significantly larger than the homogeneous line width. Under such conditions, the typical theoretical approximations concerning the decoupling of spin and charge dynamics are in general not valid anymore and the Kerr fluctuations show significantly richer detuning-dependent features in the spectral region between the two Zeeman branches. A comparison of the experimental data with an extended theory suggests that the typical Auger-recombination can be neglected at high magnetic fields in favour of a probe-laser induced photoeffect that shuffles not only the resident hole out of the quantum dot but also activates acceptor-bound holes which recharge the empty quantum dot.