INTENTIONALLY DISORDERED SUPERLATTICES WITH HIGH-DC CONDUCTANCE

We study disordered quantum-well-based semiconductor superlattices whe re the disorder is intentional and short-range correlated, Such system s consist of quantum wells of two different thicknesses randomly distr ibuted along the growth direction, with the additional constraint that wells of one kind always appears in pairs, Imperfections due to inter face roughness are considered by allowing the quantum-well thicknesses to fluctuate around their ideal values, As particular examples, we co nsider wide-gap (GaAs-Ga1-xAlxAs) and narrow-gap (InAs-GaSb) superlatt ices. We show the existence of a band of extended states in perfect co rrelated disordered superlattices, giving rise to a strong enhancement of their finite-temperature de conductance as compared to usual rando m ones whenever the Fermi level matches this band, This feature is see n to survive even if interface roughness is taken into account, Our pr edictions can be used to demonstrate experimentally that structural co rrelations inhibit the localization effects of disorder, even in the p resence of imperfections. This effect might be the basis of new, filte r-like or other specific-purpose electronic devices.