Abstract

Quantum well (QW) structures consist of alternate thin (e.g. 100 Å) layers of two different semiconductors such as GaAs and AlGaAs. Electrons and holes tend to be confined in the semiconductor with the narrower band gap (e.g. GaAs). New physical properties result from this confinement, and these properties can be engineered through choice of layer thicknesses and compositions. One specific consequence of confinement is that the optical absorption spectrum is changed significantly compared to conventional semiconductors, acquiring a steplike structure and also relatively sharp and strong absorption peaks at the edges of the steps even at room temperature. These peaks are called exciton absorption resonances, and they are normally only seen at low temperatures in conventional semiconductors.^[1]

© 1987 Optical Society of America