Bose-Einstein condensation of excitons in cuprous oxide
Snoke, David Wayne
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/19465
Description
Title
Bose-Einstein condensation of excitons in cuprous oxide
Author(s)
Snoke, David Wayne
Issue Date
1990
Doctoral Committee Chair(s)
Wolfe, J.P.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Condensed Matter
Language
eng
Abstract
Free excitons provide the only experimental system other than helium in which the behavior of particles with mass is known to follow Bose-Einstein statistics. I present experimental observations of the kinetic energy distribution of excitons in the direct-gap semiconductor Cu$\sb2$O, both the triplet orthoexciton state and the singlet paraexciton state. The density and temperature of the exciton gas closely follow the phase boundary for Bose-Einstein condensation. At the highest densities, the lower-lying paraexcitons take on an anomalous energy distribution with a sharp, high-energy edge. This odd distribution of particle energies may be associated with Bose-Einstein condensation into a state with nonzero momentum. Indeed, the excitons leave the region of their creation at supersonic velocities.
In addition to the exerimental observations, I also present theoretical models for several aspects of this non-equilibrium system. I model the equilibration of a nearly-ideal boson gas and find that a significant time is required for the approach to condensation. I also propose a new mechanism for spin-flip conversion between the orthoexciton and paraexciton states. Finally, I model the temperature and density of the excitons in steady state based on known classical kinetic effects in semiconductors, and I estimate the effects of Bose-Einstein statistics on these processes.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
