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Title: Bloch gain in dc-ac-driven semiconductor superlattices in the absence of electric domains
Authors: Hyart, Timo
Alekseev, Kirill N.
Thuneberg, Erkki V.
Issue Date: 2008
Publisher: © The American Physical Society
Citation: HYART, T., ALEKSEEV, K.N. and THUNEBERG, E.V., 2008. Bloch gain in dc-ac-driven semiconductor superlattices in the absence of electric domains. Physical Review B, 77 (16), 165330.
Abstract: We theoretically study the feasibility of amplification and generation of terahertz radiation in dc-ac-driven semiconductor superlattices in the absence of electric domains. We find that if in addition to a dc bias a strong terahertz pump field is applied, a Bloch gain profile for a small terahertz signal can be achieved under the conditions of a positive static differential conductivity. Here, the positive differential conductivity arises, similarly to the case of a large-signal amplification scheme [H. Kroemer, arXiv:cond-mat/0009311 (unpublished)], due to modifications in dc current density caused by the application of a high-frequency ac field [ K. Unterrainer et al. Phys. Rev. Lett. 76 2973 (1996)]. Whereas the sign of absorption at low and zero frequencies is sensitive to the ac fields, the gain profile in the vicinity of the gain maximum is robust. We suggest to use this ac-induced effect in a starter for a terahertz Bloch oscillator. Our analysis demonstrates that the application of a short terahertz pulse to a superlattice allows the suppression of the undesirable formation of electric domains and the achievement of a sustained large-amplitude operation of the dc-biased Bloch oscillator.
Description: This article was published in the journal, Physical Review B [© The American Physical Society]. It is also available at: http://dx.doi.org/10.1103/PhysRevB.77.165330
Version: Published
DOI: 10.1103/PhysRevB.77.165330
URI: https://dspace.lboro.ac.uk/2134/12813
Publisher Link: http://dx.doi.org/10.1103/PhysRevB.77.165330
ISSN: 1098-0121
Appears in Collections:Published Articles (Physics)

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