Short repulsive binary-alloy chains as a model for disordered quantum wells

Quantum confinement in one-dimensional disordered quantum wells is verified by means of resonant tunneling signatures in the transmission probability of an electron through barrier-well-barrier structures. The wells are simulated by short repulsive binary-alloy chains. These chains are interesting disordered systems, showing both localized and delocalized states. Bona fide confined states in the energy range where the bulk chain presents states with a localization length that exceeds at least three times the quantum-well width are found. These bona fide quantum-well states show clear symmetry properties for the envelope probability density in spite of disorder. In addition, the inadequacy of mean-field approximations to understand the quantization rules of disordered heterostructures is discussed.