Transport of free excitons and electron-hole droplets in silicon and germanium

This thesis presents the results of a wide ranging study of the transport properties of photo-excited free excitons (FE) and electron-hole droplets (EHD). The mobilities of both species are largely controlled by interaction with lattice phonons. Non-equilibrium phonon fluxes are capable of moving EHD macroscopic distances in ultrapure crystals of silicon and germanium. Both the FE and the EHD shed momentum acquired from external forces by interaction with thermal phonons. This work places on a quantitative basis the rates at which these species lose momentum as a function of both temperature and applied force. A unique method employing calibrated crystal strain gradients is developed and used to measure the mobility and other key transport parameters of the electrically neutral excitons and electron-hole droplets. With the knowledge of these parameters, the EHD is then used as a quantitative probe of nonequilibrium phonon fluxes. In addition, an unusual three-component phase transition within the electron-hole liquid is examined.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Tamor, Michael Alan

Contributors dc:contributor

• Wolfe, J.P.

• free excitons
• electron-hole droplets
• silicon
• germanium

Statement dc:rights

• 1982 Michael Alan Tamor

Language dc:language

en

Identifier

818176

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25399