Dynamic acoustic control of individual optically active quantum dot-like emission centers in heterostructure nanowires

M. Weiß, J. B. Kinzel, F. J. R. Schülein, M. Heigl, D. Rudolph, S. Morkötter, M. Döblinger, M. Bichler, G. Abstreiter, J. J. Finley, G. Koblmüller, A. Wixforth, H. J. Krenner

Nano Letters 14 2256-2264 (2014) DOI: Nano Letters

We probe and control the optical properties of emission centers forming in radial heterostructure 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 nanosecond time scale. In the spectral oscillations, we identify unambiguous signatures arising from both the mechanical and electrical component of the surface acoustic wave. In addition, different emission lines of a single emission center exhibit pronounced anticorrelated intensity oscillations during the acoustic cycle. These arise from a dynamically triggered carrier extraction out of the emission center to a continuum in the radial heterostructure. Using finite element modeling and Wentzel–Kramers–Brillouin theory we identify quantum tunneling as the underlying mechanism. These simulation results quantitatively reproduce the observed switching and show that in our systems these emission centers are spatially separated from the continuum by >10.5 nm.