Electrostatic Conveyer for Excitons

Abstract

We report on the study of indirect excitons in moving lattices -conveyers created by a set of AC voltages applied to the electrodes on the sample surface. The wavelength of this moving lattice is set by the electrode periodicity, the amplitude is controlled by the applied voltage, and the velocity is controlled by the AC frequency. We observed the dynamical localization-delocalization transition for excitons in the conveyers and measured its dependence on the exciton density and conveyer amplitude and velocity. We considered a model for exciton transport via conveyers. The theoretical simulations are in agreement with the experimental data.

Pattern formation in the exciton inner ring

“…1(a) and 1(b)]. For samples with the same layer structure, designed patterns of top electrodes create the required in-plane potential landscapes for excitons, including traps, 20 lattices, 18,23,29 ramps, 30 and circuit devices. 14,15,19,21 In this work, we use a top electrode unstructured on a large area.…”

“…10,13,24,27 A set of exciton transport phenomena was observed, including the transistor effect for excitons, 14,15,19,21 localizationdelocalization transition in random potentials 7,9,10,13,17,22 and in static and moving lattices, 18,23,29 and the inner ring in emission patterns. 7,9,17,18,26,28,29,32 The studies of the latter form the subject of this work.…”

“…Transport of indirect excitons was studied in a variety of potential landscapes created by applied electric fields, including ramps, 4,11,12,30 traps, 20 lattices, 18,29 moving lattices-conveyers, 23 narrow channels, 16,19,25 and circuit devices, 14,15,19,21 as well as in optically induced traps. 10,13,24,27 A set of exciton transport phenomena was observed, including the transistor effect for excitons, 14,15,19,21 localizationdelocalization transition in random potentials 7,9,10,13,17,22 and in static and moving lattices, 18,23,29 and the inner ring in emission patterns.…”

Exciton Transport Phenomena in GaAs Coupled Quantum Wells

“…The development of excitonic devices that control exciton fluxes is mainly concentrated on indirect excitons in coupled quantum wells (CQW) [Hagn et al, 1995;Gärtner et al, 2006;High et al, 2007;1 Vögele et al, 2009;Kuznetsova et al, 2010b;Cohen et al, 2011;Winbow et al, 2011;Schinner et al, 2011;Leonard et al, 2012] and excitonpolaritons in microcavities [Amo et al, 2010;Gao et al, 2012;Ballarini et al, 2013;Nguyen et al, 2013;Sturm et al, 2014].…”

Transport of indirect excitons in a potential energy gradient

“…Furthermore, indirect excitons have a built-in dipole moment ed, where d is close to the distance between the quantum well (QW) centers that allows their energy to be controlled by voltage: an electric field F z perpendicular to the QW plane results in the exciton energy shift E = edF z 11 . These properties allow studying transport of indirect excitons in electrostatically created in-plane potential landscapes E(x, y) = edF z (x, y).Exciton transport was studied in various electrostatic potential landscapes including circuit devices 12-14 , traps 15 , lattices 16,17 , moving lattices -conveyerscreated by a set of ac voltages 18 , and narrow channels 14,19,20 .Several exciton transport phenomena have been observed, including the inner ring in emission patterns 4,6,8,10,21,22 , transistor effect for excitons [12][13][14] , localization-delocalization transition in random potentials 4,6,8 and in lattices 16,17 , and dynamical localization-delocalization transition in conveyers 18 . Exciton transport was also studied in potential energy gradients created by voltage gradients in electrodes 1,7 .…”