Carrier confinement in disordered GaAs/AlAs superlattices probed by capacitance–voltage experiments

The effects of the intentional disorder in (GaAs)m/(AlAs)6 superlattices were studied using transport techniques. Evidences of a strong electron localization in the superlattices even in the presence of extend states were found. We interpret this result taking into account the disorder which causes the local breakdown of the coherence of the miniband transport and, therefore, give rise to the electron localization. In order to support our experiments, we numerically calculate the capacitance–voltage characteristics of the superlattices and the results were found in good agreement with the measured ones.