N.V. Danko − Master of the 2nd year of study, NRNU MEPhI;

Engineer, Kotel’nikov Institute of Radioengineering ang Electronics of RAS (Moscow)

E-mail: nvdanko@mail.ru

I.V. Altukhov – Dr.Sc. (Phys.-Math.), Principal Research Scientist,

Kotel’nikov Institute of Radioengineering ang Electronics of RAS (Moscow)

E-mail: alt@cplire.ru

M.S. Kagan – Dr.Sc. (Phys.-Math.), Principal Research Scientist,

Kotel’nikov Institute of Radioengineering ang Electronics of RAS (Moscow)

E-mail: kagan@cplire.ru

S.K. Paprotsky – Ph.D. (Phys.-Math.), Senior Research Scientist,

Kotel’nikov Institute of Radioengineering ang Electronics of RAS (Moscow)

E-mail: s.paprotskiy@gmail.com

N.A. Khvalkovsky − Ph.D. (Phys.-Math.), Senior Research Scientist,

Kotel’nikov Institute of Radioengineering ang Electronics of RAS (Moscow)

E-mail: nik@cplire.ru

I.S. Vasilievsky – Dr.Sc. (Phys.-Math.), Assistant Professor, 

NRNU MEPhI (Moscow)

E-mail: ivasilevskii@mail.ru

A.N. Vinichenko − Ph.D. (Phys.-Math.), Research Scientist,

NRNU MEPhI (Moscow)

E-mail: anvinichenko@mephi.ru

Problem formulating. Studies of semiconductor superlattices (SLs) are of interest, first, in connection with quantum tunneling character of current (up to room temperature) and, second, owing to the predicted amplification of Bloch electronic waves, which is promising for development of tunable THz sources. The main hindrance to the Bloch wave amplification is the formation of electrical domains owing to the static negative differential conductivity (NDC) of SLs, which eliminates the Bloch gain. 

On the other hand, the samples with the electrical domains exhibit the dynamic NDC (the real part of electrical impedance is negative) in some frequency range and can be used for high-frequency generation in a suitable resonant cavity. We observed the excitation of a THz cavity owing to the negative resistance of the superlattice with domains. The conditions for the generation should depend on domain regimes.

Goal. Many works were devoted also to studies of domain regimes. Most of them were performed with weakly doped SLs at low temperatures under strong illumination. The change in free carrier concentration under illumination gives rise to different domain regimes. It has been shown, in particular, that transition from travelling to static domain regime occurs at sufficiently high illumination intensity. The aim of this work was to study the effect of rather weak interband illumination on the tunneling current in high-doped short-period GaAs/AlAs superlattices with high-field domains.

Result. The effect of strong influence of weak illumination on conductivity of SL with the domains in conditions when usual photoconductivity is practically absent (rather high doping level) is observed for the first time. The high photoresponse of short-period GaAs/AlAs SLs at high voltages to the relatively weak interband illumination is connected with transformations of high-field domains with extended region of depopulated donors, where the intrinsic free electron concentration is extremely low. The sufficiently intense illumination could initiate the traveling-to-static domain transition, which becomes apparent in the current saturation region in I-V curves.

Practical meaning. The effect of strong influence of weak illumination on conductivity of SL with the domains can be used, in particular, for simple controlling the domain regimes.

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