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Hydrodynamics of indirect excitons in coupled quantum wells

Wilkes, Joe 2012. Hydrodynamics of indirect excitons in coupled quantum wells. PhD Thesis, Cardiff University.
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Abstract

This thesis comprises a theoretical study of the dynamics of indirect excitons in coupled quantum wells at low lattice temperatures. The results of numerical simulations of the exciton photoluminescence pattern are presented and compared to available experimental data. The in-plane transport of quantum well excitons created by laser excitation is modeled using a non-linear drift-diffusion equation. Combined with a model of exciton relaxation thermodynamics, a complete description of the evolution of the exciton density and temperature is built. The optical decay of indirect excitons is included in the modeling. This is used to make predictions of the spatial photoluminescence patterns which have been observed experimentally. The transport of dipole orientated excitons via externally applied electrostatic potentials is also studied. The drift-diffusion equation is adapted to include the inplane electric field. This is done for some specific forms of the potential landscapes such as a linear potential energy gradient and a propagating lattice. These correspond to some recent experiments for which results are available. The combined theoretical and experimental studies reveal a deeper insight into the transport properties of indirect excitons. Finally, the external ring structure in the indirect exciton emission pattern is studied. Its formation is modeled using a set of coupled transport equations for electrons, holes and indirect excitons. The Coulomb interactions between all three species are incorporated in the model. It is shown that these interactions lead to an instability in the external ring and are responsible for its fragmentation into a periodic array of islands which has been observed experimentally.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Uncontrolled Keywords: Indirect excitons ; dipolar excitons ; quantum wells ; photoluminescence ; transport ; thermalization ; dirsorder, photon cone ; inner ring ; external ring ; ring fragmentation ; macroscopic ordering ; electrostatic conveyer
Funders: EPSRC
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 04:42
URI: http://orca.cf.ac.uk/id/eprint/43296

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