Dynamic Acoustic Control of Individual Optically Active Quantum Dot-like Emission Centers in Heterostructure Nanowires

TL;DR

This study demonstrates dynamic control of quantum-dot-like emission centers in heterostructure nanowires using surface acoustic waves, revealing insights into their optical properties and carrier dynamics.

Contribution

It introduces a method to manipulate emission energy and occupancy of quantum dots in nanowires with surface acoustic waves, combining experimental and theoretical analysis.

Findings

Surface acoustic waves can modulate emission energy and occupancy.

Quantum tunneling explains carrier extraction dynamics.

Quantum dots are spatially separated from the continuum by over 10.5 nm.

Abstract

We probe and control the optical properties of emission centers forming in radial het- erostructure GaAs-Al0.3Ga0.7As nanowires and show that these emitters, located in Al0.3Ga0.7As layers, can exhibit quantum-dot like characteristics. We employ a radio frequency surface acoustic wave to dynamically control their emission energy and occupancy state on a nanosec- ond timescale. In the spectral oscillations we identify unambiguous signatures arising from both the mechanical and electrical component of the surface acoustic wave. In addition, differ- ent emission lines of a single quantum dot exhibit pronounced anti-correlated intensity oscilla- tions during the acoustic cycle. These arise from a dynamically triggered carrier extraction out of the quantum dot to a continuum in the radial heterostructure. Using finite element modeling and Wentzel-Kramers-Brillouin theory we identify quantum tunneling as the underlying mech- anism. These simulation results quantitatively reproduce the observed switching and show that in our systems these quantum dots are spatially separated from the continuum by > 10.5 nm.