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Current issue   Ukr. J. Phys. 2014, Vol. 59, N 1, p.50-57

    Paper

Lysiuk I.O.1, Olikh Ya.M.1, Olikh O.Ya.2, Beketov G.V.1

1 V.E. Lashkaryov Institute of Semiconductor Physics, Nat. Acad. of Sci. of Ukraine
(41, Nauky Ave., Kyiv 03028, Ukraine; e-mail: jaroluk3@ukr.net)
2 Taras Shevchenko National University of Kyiv, Faculty of Physics
(64, Volodymyrs’ka Str., Kyiv 01601, Ukraine; e-mail: olikh@univ.kiev.ua)

Features of Ultrasound Absorption by Dislocations in Subgrain-Free Cs0.2Hg0.8Te Crystals

Section: Solid matter
Original Author's Text: Ukrainian

Abstract: The temperature dependence of the ultrasound wave absorption in bulk p-Cd0.2Hg0.8Te crystals free from low-angle grain boundaries has been studied experimentally for the first time in the frequency range 10–55 MHz and the temperature interval 150–300 K, and the corresponding results of measurements are presented. The maximum value of absorption coefficient is found to increase and to shift toward higher temperatures, as the ultrasound frequency grows. The results obtained can be satisfactorily explained in the framework of the Brailsford model, which associates the ultrasound absorption with vibrations of thermally activated dislocation kinks. The characteristic parameters of this model for p-Cd0.2Hg0.8Te are determined; namely, the frequency coefficient fk ≈ 6 × 109 Hz and the kink diffusion activation energy Wk ≈ 0.11 eV. The dislocation concentration is also evaluated (α ≈ 2 × 1010 m-2), with the determined value being consistent with that obtained by the selective etching method (0.7 × 1010 m-2).

Key words: ultrasound, dislocations, CdxHg1-xTe