Acoustically regulated carrier injection into a single optically active quantum dot

TL;DR

This study demonstrates how radio frequency surface acoustic waves can precisely control carrier injection into a single quantum dot, influencing exciton formation pathways and enabling acousto-electric transport for quantum optoelectronic applications.

Contribution

It introduces a method to regulate carrier injection into a quantum dot using surface acoustic waves, revealing formation pathways and transport mechanisms in the time domain.

Findings

Exciton emission intensities are programmed by the acoustic cycle.

Both neutral and charged excitons can be formed optically or via acoustic injection.

Experimental results match calculated electron and hole trajectories.

Abstract

We study the carrier injection into a single InGaAs/GaAs quantum dot regulated by a radio frequency surface acoustic wave. We find that the time of laser excitation during the acoustic cycle programs both the emission intensities and time of formation of neutral $(X^0)$ and negatively charged $(X^-)$ excitons. We identify underlying, characteristic formation pathways of both few-particle states in the time-domain experiments and show that both exciton species can be formed either with the optical pump or at later times by injection of single electrons and holes "surfing" the acoustic wave. All experimental observations are in excellent agreement with calculated electron and hole trajectories in the plane of the two-dimensional wetting layer which is dynamically modulated by the acoustically induced piezoelectric potentials. Taken together, our findings provide insight on both the onset of acousto-electric transport of electrons and holes and their conversion into the optical domain after regulated injection into a single quantum dot emitter.