27 research outputs found
Suppressed absolute negative conductance and generation of high-frequency radiation in semiconductor superlattices
We show that space-charge instabilities (electric field domains) in
semiconductor superlattices are the attribute of absolute negative conductance
induced by small constant and large alternating electric fields. We propose the
efficient method for suppression of this destructive phenomenon in order to
obtain a generation at microwave and THz frequencies in devices operating at
room temperature. We theoretically proved that an unbiased superlattice with a
moderate doping subjected to a microwave pump field provides a strong gain at
third, fifth, seventh, etc. harmonics of the pump frequency in the conditions
of suppressed domains.Comment: 8 pages. Development of cond-mat/0503216 . Version 2: Final version,
erratum is include
Nonequilibrium phenomena in high Landau levels
Developments in the physics of 2D electron systems during the last decade
have revealed a new class of nonequilibrium phenomena in the presence of a
moderately strong magnetic field. The hallmark of these phenomena is
magnetoresistance oscillations generated by the external forces that drive the
electron system out of equilibrium. The rich set of dramatic phenomena of this
kind, discovered in high mobility semiconductor nanostructures, includes, in
particular, microwave radiation-induced resistance oscillations and
zero-resistance states, as well as Hall field-induced resistance oscillations
and associated zero-differential resistance states. We review the experimental
manifestations of these phenomena and the unified theoretical framework for
describing them in terms of a quantum kinetic equation. The survey contains
also a thorough discussion of the magnetotransport properties of 2D electrons
in the linear response regime, as well as an outlook on future directions,
including related nonequilibrium phenomena in other 2D electron systems.Comment: 60 pages, 41 figure