Time-resolved Raman scattering in GaAs multiple quantum well structures

This thesis describes an optical study of the intersubband relaxation of carriers in GaAs multiple quantum well structures. For this investigation the application of the conventional Raman scattering technique was extended to the picosecond time domain. Inelastic light scattering from the elementary intersubband excitations of an electron-hole plasma reveals both the absolute carrier density and the occupancy of the electronic subbands of a GaAs quantum welL The major result of this investigation concerns the role of the intersubband scattering processes in the relaxation of carriers following their excitation in a GaAs quantum well by a short optical pulse. Carriers generated on the second subband of a wide quantum well relax towards the bottom of the well by the emission of acoustic phonon. Their lifetime is found equal to 325±25 picoseconds in a 215 A multiple quantum well structure, whereas in a narrower well (116 A) the lifetime is reduced behond our experimental time resolution of 8 ps, presumably caused by the faster relaxation mechanism corresponding to the emission of an optical phonon. A theoretical calculation of the scattering rate by longitudinal acoustic phonon supports the existence of a long-lived electron population on the second subband of a wide GaAs quantum well.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Oberli, Daniel Yves

Contributors dc:contributor

• Klein, Miles V.

• time-resolved Raman scattering
• GaAs
• multiple quantum well structures
• intersubband relaxation

Statement dc:rights

• 1988 Daniel Yves Oberli

Language dc:language

en

Identifier

3471802

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23899