Quantum interference and localization in disordered GaAs/AlGaAs superlattices

(T)he coherence and the dimensionality of electrons were studied in the intentionally disordered GaAs/AlGaAs superlattices where the disorder was produced either by the random variation of the well thicknesses or by the interface roughness. Depending on relative values of the disorder energy and the Fermi energy the coherent and incoherent diffusive transport regimes were distinguished and the disorder driven metal-to-insulator transition was achieved. The qualitatively different magnetoresistances with the positive and negative concavities were observed in the metallic and insulating samples respectively. Good agreements were found with the theories developed in the limits of the weak and strong disorder. The localization properties of the single-particle excitations were compared with those of the collective excitations.