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ALT'23 The 30th International Conference on Advanced Laser Technologies
N-I-13
Nonequilibrium transport in Hg1-xCdxTe-based heterostructures induced by terahertz laser radiation
A. Kazakov1, A. Galeeva1, A. Artamkin1, A. Ikonnikov1, S. Chmyr1, S. Dvoretskiy2, N. Mikhailov2, V. Bannikov3, S. Danilov4, L. Ryabova1, D. Khokhlov13
1-M.V. Lomonosov Moscow State University, Physics Department, Leninskiye Gory, 1-2, Moscow, 119991, Russia 2- Rzhanov Institute of Semiconductor Physics of the Siberian Branch of the RAS, Lavrentyev Avenue 13, Novosibirsk,
630090, Russia
3- The Lebedev Physical Institute of the RAS, 119991, 119991, Moscow, Leninsky Avenue, 53 4- Faculty of Physics, University of Regensburg, Regensburg D-93053, Germany
Main author email address: askazakov@physics.msu.ru
Transport properties of topologically nontrivial materials are of a great applied and fundamental interest. Hgi-xCdxTe solid solutions exhibit a composition-driven topological transition from the trivial semiconductor phase (x > 0.16), characterized by the direct energy band ordering, to the topological phase ^ < 0.16) with the inverted energy spectrum. Terahertz optoelectrical probing may provide an experimental observation of topological conductive states in Hgi-xCdxTe solid solutions due to relatively low bulk carrier concentration. In this work, we study terahertz photoconductivity in Hgi-xCdxTe epitaxial films in a close vicinity to the alloy composition x ~ 0.16, which corresponds to the topological phase transition.
Hgi-xCdxTe-based heterostructures (0.12 < x < 0.16) with active layer thickness d ~ 4 ^m were synthesized on a semi-insulating GaAs [013] substrate with ZnTe and CdTe buffer layers by means of molecular beam epitaxy. Transport properties of the structures were studied in the 4.2 - 300 K temperature range. All the samples were of the n-type. The typical bulk concentration was ~ 1014 cm-3 at T = 4.2 K. Terahertz photoconductivity stimulated by 100 ns laser pulses was studied in the frequency range 0.6 - 3.9 THz in magnetic fields up to 4 T at T = 4.2 K. The samples under study were prepared with both the standard Hall bar sample geometry and the nonlocal H-bar-like geometry with various geometrical parameters. We show that the photoresponse in the topologically nontrivial phase (x < 0.16) demonstrates strong asymmetry in a magnetic field which is absent in the trivial phase samples (x > 0.16) [1]. Also, the photoresponse kinetics strongly depends on the position of potential probes on the sample which is not due to possible structure inhomogeneity. Moreover, the photoresponse in topological phase of Hg1-xCdxTe-based heterostructures incorporates a chiral nonlocal contribution indicating the formation of edge conductive channels [2]. We discuss the photoconductivity features in terms of a qualitative model that takes into account the coexistence of bulk transport and boundary conductive channels. The work was supported by the Russian Science Foundation, grant #19-12-00034.
[1] A.V. Galeeva, A.S. Kazakov, A.I. Artamkin, L.I. Ryabova, S.A. Dvoretskiy, N.N. Mikhailov, M.I. Bannikov, S.N. Danilov, D.R. Khokhlov, Sci. Rep. 2020, 10, 2377.
[2] A.S. Kazakov, A.V. Galeeva, A.I. Artamkin, A.V. Ikonnikov, L.I. Ryabova, S.A. Dvoretskiy, N.N. Mikhailov, M.I. Bannikov, S.N. Danilov, D.R.
Khokhlov, Sci. Rep. 2021, 11(1), 1587.
