Resonant Optical Spectroscopy Of Semiconductor Microstructures.pdf

Resonant Optical Spectroscopy of Semiconductor
Microstructures
E. L. Ivchenko
A. F. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russia
Abstract: Optical spectroscopy based on light reflection and transmission mea-
surements, Raman scattering, polarized photoluminescence and four-wave mixing
is a powerful tool to investigate the fine structure of exciton levels and excitonic ki-
netics in semiconductor microstructures. The efficiency of spectroscopic methods is
demonstrated for excitons in various kinds of nanostructures: exciton polaritons in
long-period multiple quantum wells, in particular in resonant Bragg and anti-Bragg
structures, localized excitons in type II GaAs/AIAs superlattices, excitons local-
ized on anisotropic islands in type I quantum wells and confined in semiconductor
nanocrystals, and exciton polaritons in microcavities with embedded quantum wells
or gratings of quantum wires. The exchange and Zeeman splittings are shown to be
extremely sensitive to the structure geometry and the shape of the exciton envelope
function.
1 Introduction
If allowance is made for flee-carrier spin degeneracy, then the exciton energy levels are
degenerate, even in the case of simple bands. The ground-state degeneracy is given by
the product of the conduction- and valence-band degeneracies at the extremum point.
The short-range electron-hole exchange interaction partially removes this degeneracy,
the long-range exchange interaction and the coupling with photons (or the polariton
effect) give rise to additional splittings between the branches of the free-exciton dis-
persion curve or between sublevels of localized excitons. Due to the Zeeman effect,
an external ic field can further modify the fine structure of excitonic states. The
aim of the present paper is to display the rich possibilities of various spectroscopic
methods to study optical properties of semiconductor nanostructures with emphas