Publication: Intentionally disordered superlattices with high-dc conductance
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1995-11
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IEEE-Inst Electrical Electronics Engineers Inc.
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Abstract
We study disordered quantum-well-based semiconductor superlattices where the disorder is intentional and short-range correlated, Such systems consist of quantum wells of two different thicknesses randomly distributed along the growth direction, with the additional constraint that wells of one kind always appears in pairs, Imperfections due to interface roughness are considered by allowing the quantum-well thicknesses to fluctuate around their ideal values, As particular examples, we consider wide-gap (GaAs-Ga1-xAlxAs) and narrow-gap (InAs-GaSb) superlattices. We show the existence of a band of extended states in perfect correlated disordered superlattices, giving rise to a strong enhancement of their finite-temperature de conductance as compared to usual random ones whenever the Fermi level matches this band, This feature is seen to survive even if interface roughness is taken into account, Our predictions can be used to demonstrate experimentally that structural correlations inhibit the localization effects of disorder, even in the presence of imperfections. This effect might be the basis of new, filter-like or other specific-purpose electronic devices.
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© IEEE-Inst Electrical Electronics Engineers Inc.
It is with great pleasure that we thank collaboration and illuminating conversations with Fernando Agulló-Rueda. Work at Leganés is supported by the DGICyT (Spain) through project PB92-0248, and by the European Union Human Capital and Mobility Programme through contract ERBCHRXCT930413. Work at Madrid is supported by UCM through project PR161/93-4811.
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[15] We have confirmed this assertion by using the Poincare-map formalism developed by us in Ref. [5], which allows us to study transmission properties of a disordered SL of finite length embedded in an infinite and periodic (dA = a) SL; we do not dwell further in this matter because this work is devoted to the study of realistic superlattices which can be built and measured.