Optical studies of many body effects in semiconductor quantum wells.

A sandwich of two semiconductors with different band gaps (typically a thin, ~5nm, layer of GaAs within Al_{x}Ga_{1-x}As) causes the confinement of electrons to a two dimensional plane. Optical measurements generally convey a great deal of information on the states of these two dimensional electrons. One area of considerable interest is the response of these electrons to the creation or annhilation of a positively charged valence band hole during an optical experiment. Sharp features called Fermi Edge Singularities are observed due to these many body effects.

Our recent success in studying n-type quantum wells [1, 2] at zero magnetic field has opened up a number of possibilities for further research. In particular, the following new experiments are suitable for Honours level projects in 1998: (a) a study of many body effects in n-type samples at high magnetic fields 
(b) a study of the Fermi Edge Singularity in a range of new p-type samples (i.e. where the majority carriers are valence band holes)

  1. S A Brown, J F Young, Z Wasilewski and P T Coleridge, 'Fermi Edge Singularities in Photoluminescence from Modulation Doped GaAs Quantum Wells', Physical Review B 56, 3937 (1997).
  2. S A Brown, J F Young, J A Brum, P Hawrylak, and Z Wasilewski, 'Evolution of the Interband Absorption Threshold with the Density of a Two Dimensional Electron Gas', Physical Review B (Rapid Communications) 54, 11082 (1996).