Inverse photoemission from semiconductors

Inverse photoemission makes it possible to obtain the complete information about unoccupied electronic states by determining the full set of quantum numbers. This review includes an introduction to the technique, and its applications to semiconductors, insulators and high temperature superconductors. Examples cover the band dispersion of conduction bands and two-dimensional electronic states at surfaces, interfaces and overlayers. A variety of topics can be addressed by inverse photoemission, such as the concepts of quasiparticles and self-energy, the layer-by-layer change in the electronic structure at an interface, and the nature of the hole states that cause high temperature superconductivity.