University of Illinois Urbana-Champaign

Luminescence Studies of the Excitonic System in Germanium: Phase Properties and Transport

Simon, Andrew Herbert

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/2142/77429

Description

Title
Luminescence Studies of the Excitonic System in Germanium: Phase Properties and Transport
Author(s)
Simon, Andrew Herbert
Issue Date
1988
Doctoral Committee Chair(s)
Wolfe, James 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
  • This thesis presents the results of three studies of the excitonic system in Ge. These studies employ near-infrared spectroscopy and imaging techniques to examine the phase and transport properties of the low temperature exciton-plasma system.
  • The first study, presented in Chapter II, examines the properties of the electron-hole liquid (EHL) phase as a function of $\langle$111$\rangle$-uniaxial stress. The application of stress along a $\langle$111$\rangle$ axis greatly reduces the degeneracy of the conduction and valence bands, thereby reducing the stability of the EHL. This thesis reports the first observation of the EHL in the high-stress limit ($\sigma$ $>$ 70 kgf/mm$\sp2$). The observation of the EHL in this high-stress regime serves as an important confirmation of theoretical calculations of EHL properties. The success of this experiment can be attributed to the use of the nonuniform Hertzian stress geometry.
  • The second study, presented in Chapter III, uses time-resolved spectroscopy to study the phase properties of the exciton gas, EHL, and electron-hole plasma (EHP) in unstressed Ge. A detailed spectroscopic analysis of spectra taken near and above the liquid-gas critical temperature is presented. By employing ana analysis using three components (excitons, excitonic complexes, and EHP), evidence is found for a second exciton-plasma condensation at temperatures above the EHL critical temperature. A phase diagram for the excitonic system is proposed that includes the second condensed phase.
  • Uniaxial stress is used to study the electron-hole droplet (EHD) cloud in Chapter IV. By applying stress along a $\langle$110$\rangle$ axis, the two conduction band valleys perpendicular to the stress axis can be emptied of electrons in the EHL phase. This alteration of the electron Fermi surface causes remarkable changes to occur in the anisotropic EHD cloud structure. The changes in the cloud structure illustrate the important role that the anisotropic Fermi surface plays in giving the cloud its shape.
Graduation Semester
1988
Type of Resource
text
Permalink
http://hdl.handle.net/2142/77429

Owning Collections

Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Physics
Dissertations in Physics