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  • Ескіз
    Публікація
    Peculiarities of concentration dependences of thermal conductivity in (PbTe)₁₋ₓ (Bi₂Te₃)ₓ semiconductor solid solutions
    (Інститут термоелектрики НАН України, 2014) Rogacheva, E. I.; Vodorez, O. S.; Nashchekina, O. N.; Dresselhaus, M. S.
    For the semiconductor (PbTe)₁₋ₓ (Bi₂Te₃)ₓ solid solutions, the temperature (T = 250 – 670 K) and concentration (x = 0 – 0.07) dependences of the total λ and lattice λp thermal conductivities were obtained. It was established that the dependences λ(x), λp(x) and β(x) (where β is the exponent in the λp ~ T⁻ᵝ dependence) have a non-monotonic dependence on x in this range of x. While showing a general tendency to decrease with increasing x, the three variables λ, λp, and β exhibit maxima at x = 0.005, 0.015 and x = 0.03. The oscillatory character of these dependences is attributable to the changes in thermal transfer processes and the mechanisms of phonon scattering under transitions from the dilute to the concentrated and associated solid solutions, with the transitions due to spatial ordering processes. The effective cross-section σs for phonon scattering by impurity atoms was estimated on the basis of the experimental data and theoretical calculations in accordance with the Klemens theory. The mean σs value in the homogeneity region of PbTe (x = 0 – 0.05) found experimentally coincides with the theoretically calculated σs value. However, in the region of the dilute solid solutions (x < 0.005), the σs value considerably exceeds the mean σs value. Also long-term aging reduces λ by ~ 15%.
  • Ескіз
    Документ
    Temperature dependences and isotherms of galoanomagnetic properties of Bi doped PbTe crystals and thin films
    (Науково-технологічний комплекс "Інститут монокристалів", 2006) Rogacheva, E. I.; Lyubchenko, S. G.; Vodorez, O. S.
    The temperature dependences of galvanomagnetic properties (the Hall coefficient, electrical conductivity, charge carrier mobility) of (PbTe)₁₀₀₋ₓBiₓ (x = 0-1) alloys obtained by doping PbTe with elementary Bi and thin films prepared from these alloys were studied in the temperature range 80-300 K. On the basis of the temperature dependences, the isotherms of the properties on the Bi concentration, which had been observed earlier at room temperature, is preserved at lower temperatures. This confirms our earlier suggestion about the self-organization processes taking place in the defect subsystem of the crystal at certain Bi concentrations.
  • Ескіз
    Публікація
    Enhancement In Charge Carrier Mobility Under Transition To Heavy Doping
    (2010) Rogacheva, E. I.; Nashchekina, O. N.; Vodorez, O. S.
    New experimental data confirming our suggestion about the universal character of critical phenomena accompanying the transition from "an impurity gas" to "an impurity condensate" with impurity concentration increasing are presented. The existence of the range of anomalous growth in the charge carrier mobility under transition to heavy doping is established for PbTe–PbSe solid solutions. The experimental results are analyzed on the basis of percolation theory taking into account alloy scattering and spatial correlations of impurity centers.