Quantum Wells and Superlattices

Abstract

The Quantum Well (QW) is a system in which the electron motion is restricted in one direction thus producing quantum confinement; in other words, the spectrum in one of the quantum numbers changes from continuous to discrete. The quantum wells represent an example of systems with reduced dimensionality. Systems with electron motion restricted in two directions are called quantum wires, and those confined in all three directions were given the name of quantum dots. For quantum confinement to be observable, the size of a well must be less than the electron mean-free path. This requirement imposes constraints both on the geometric size of a well and on the quality of the sample and temperature determining the mean-free-path length.