Abstract

We are exploring resonant three-wave mixing as a spectroscopic probe of interband and intersubband excitations at semiconductor surfaces and interfaces (e.g., heterojunctions) and in quantum wells. Three-wave mixing at either a semiconductor surface or heterojunction, or in an asymmetric quantum well, involves contributions from electric field-induced optical interband and intersubband transitions and can, therefore, take place in centrosymmetric as well as noncentrosymmetric semiconductors. On the other hand, three-wave mixing in a symmetric quantum well is normally forbidden but can take place in the presence of a perpendicular electric field. Unlike Raman scattering, three-wave mixing can also be used to probe transitions between subbands that are unoccupied. We note moreover that, in the case of quantum wells, three-wave mixing can be used to probe intersubband excitations between subbands in the valence band and subbands in the conduction band and that, in the case of spatially confined levels at a semiconductor surface or a heterojunction, it can be used to probe transitions between subbands in two valence bands or two conduction bands.

© 1987 Optical Society of America