3,212 research outputs found
Quasi-Ballistic Electron Transport in Random Superlattices
We theoretically study electron transport in disordered, quantum-well based,
semiconductor superlattices with structural short-range correlations. Our
system consists of equal width square barriers and quantum wells with two
different thicknesses. The two kinds of quantum wells are randomly distributed
along the growth direction. Structural correlations are introduced by adding
the constraint that one of the wells always appears in pairs. We show that such
correlated disordered superlattices exhibit a strong enhancement of their dc
conductance as compared to usual random ones, giving rise to quasi-ballistic
electron transport. Our predictions can be used to demonstrate experimentally
that structural correlations inhibit the localization effects of disorder. We
specifically describe the way superlattices should be built and experiments
should be carried out for that purpose.Comment: REVTeX 3.0, 7 pages, 4 figures on request from FD-A
([email protected]). Submitted to Physical Review B. Preprint
MA/UC3M/12/199
Absence of localization and large dc conductance in random superlattices with correlated disorder
We study how the influence of structural correlations in disordered systems
manifests itself in experimentally measurable magnitudes, focusing on dc
conductance of semiconductor superlattices with general potential profiles. We
show that the existence of bands of extended states in these structures gives
rise to very noticeable peaks in the finite temperature dc conductance as the
chemical potential is moved through the bands or as the temperature is
increased from zero. On the basis of these results we discuss how dc
conductance measurements can provide information on the location and width of
the bands of extended states. Our predictions can be used to demonstrate
experimentally that structural correlations inhibit the localization effects of
disorder.Comment: REVTeX 3.0, 14 pages, 11 figures available on request from ED
([email protected]). Submitted to Phys Rev B. MA/UC3M/06/9
Excitation decay in one-dimensional disordered systems with paired traps
Incoherent transport of excitations in one-dimensional disordered lattices
with pairs of traps placed at random is studied by numerically solving the
corresponding master equation. Results are compared to the case of lattices
with the same concentration of unpaired traps, and it is found that pairing of
traps causes a slowdown of the decay rate of both the mean square displacement
and the survival probability of excitations. We suggest that this result is due
to the presence of larger trap-free segments in the lattices with paired
disorder, which implies that pairing of traps causes less disruption on the
dynamics of excitations. In the conclusion we discuss the implications of our
work, placing it in a more general context.Comment: REVTeX 3.0, 10 pages, 7 figures available on request from FD-A
([email protected]), Universidad Carlos III preprint MA/UC3M/08/9
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