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Electrical Current Injection into Exciton-Polariton Condensates and Polariton-Enhanced Exciton Transport

Myers, David M. (2019) Electrical Current Injection into Exciton-Polariton Condensates and Polariton-Enhanced Exciton Transport. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Exciton-polaritons are composite quasiparticles that are the result of coupling excitons with photons. They bring together many of the advantages of both underlying parts: The excitons lend their strong interactions, and the photons give an extremely light mass. Polaritons exist in solid-state systems, which gives them a high potential for device applications, especially as their most interesting quantum effects, Bose-Einstein condensation in particular, become accessible at higher temperatures.

In this thesis, I focus primarily on the effects of injecting electrical current into a polariton condensate. I was able to take advantage of the well-established fabrication methods for GaAs-based systems, as well as the high-quality samples developed by my predecessors, which allow the formation of nearly equilibrium condensates over large areas. My colleagues and I then made devices that allow direct injection of electrical charge carriers through polariton condensates in an in-plane direction of the 2D system. I report here three major observations. The first is a superlinear increase in photocurrent, which we attribute to stimulation of an Auger-like scattering of excitons into both the condensate and free carrier states. The second is an increase in the condensate density with current injection, which we explain as stimulated pairing of injected free electrons with intrinsic free holes. The third effect is a shift in the in-plane momentum of polariton condensates with injected current, which is evidence of drag on the polaritons by the free electrons.

In addition to the work with electrical current injection, I also report on exciton transport distances in the polariton system. Specifically, very highly excitonic particles are found far from the creation point, with transport distances comparable to those of the much more photonic polaritons. We explain this as an effect of the unusual shape of the polariton energy dispersion.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Myers, David M.dmm154@pitt.edudmm1540000-0001-8060-9200
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSnoke, David
Committee MemberFreitas,
Committee MemberDevaty,
Committee MemberLiu, W.
Committee MemberTowe, Eliastowe@cmu
Date: 20 June 2019
Date Type: Publication
Defense Date: 22 March 2019
Approval Date: 20 June 2019
Submission Date: 11 April 2019
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 234
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Bose-Einstein condensate, semiconductor, quantum wells, gallium arsenide, photoluminescence, optics, device fabrication, lasers
Date Deposited: 20 Jun 2019 16:49
Last Modified: 20 Jun 2019 16:49


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