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Quantum Size Effects and Transport Phenomena in PbSe Quantum Wells and PbSe/EuS Superlattices
(AIP Publishing LLC, 2013) Rogacheva, E. I.; Nashchekina, O. N.; Olkhovskaya, S. I.; Sipatov, A. Yu.; Dresselhaus, M. S.
It is established that the room-temperature dependences of transport properties on the total thickness of PbSe layers d in PbSe/EuS superlattices exhibit an oscillatory behavior. It is shown that the oscillation period Δd practically coincides with the period of the thickness oscillations observed earlier in single PbSe/EuS quantum well. The non-monotonic character of these dependences is attributed to quantum size effects. The theoretically estimated and experimentally determined Δd values are in good agreement.
Dependences of thermoelectric properties on the thickness of thin films of indium doped lead telluride
(Institute of Thermoelectricity, 2014) Menshikova, S. I.; Rogacheva, E. I.; Sipatov, A. Yu.; Matychenko, P. V.; Dobrotvorskaya, M. V.
Dependences of thermoelectric properties (the Seebeck coefficient S, the electric conductivity σ, the Hall coefficient RH, the carrier mobilityμ and the thermoelectric power P = S²·σ) on the thickness d (d = 10 – 255 nm) of thin films prepared by vacuum evaporation of indiumdoped PbTe crystals and subsequent condensation on (111) BaF₂ substrates were obtained. With decreasing thickness of films to d ≈ 40 nm, there is n- to p-type inversion of conduction which is related to a change in thermodynamic equilibrium conditions and partial reevaporation of lead and/or indium atoms. Extremes were found on the thickness dependences of properties at d₁ ≈ 20 nm which is indicative of hole gas quantization. In the range of thicknesses with n-type conduction there is a smooth change in thermoelectric properties with thickness which testifies to manifestation of classical size effect and is sufficiently well described in the framework of the Fuchs-Sondheimer theory.
Size effects in thin n-PbTe films
(STC "Institute for Single Crystals", 2015) Menshikova, S. I.; Rogacheva, E. I.; Sipatov, A. Yu.; Zubarev, Evgeniy N.
Size effects in chlorine doped PbSe thin films
(Institute of Thermoelectricity, 2015) Menshikova, S. I.; Rogacheva, E. I.; Sipatov, A. Yu.; Krivonogov, S. I.; Matychenko, P. V.
The possibility of obtaining strongly degenerate (≈ 3·10²⁰ сm⁻³) PbSe thin films (d = 5 – 220 nm) with n-type conductivity by thermal evaporation in vacuum of PbSe crystals doped with PbCl₂, with subsequent condensation onto (001) KCl substrates was established. It was shown that the films had high homogeneity degree, no grain structure was observed. The thickness dependences of thermoelectric properties (the Seebeck coefficient S, the Hall coefficient RH and the electric conductivity σ) of thin films were obtained. In the thickness range d ≈ 5 ÷ 30 nm, oscillation properties were observed with growth of d that are attributable to electron gas quantization. The calculation of S(d) dependence on the assumption of size quantization with regard to contribution of several subbands and the thickness dependence of the Fermi energy was shown to be in agreement with the experimental data. In the region of d > 30 nm there was growth of S and σ with thickness, which is attributable to manifestation of classical size effect and interpreted in the framework of Fuchs-Sondheimer and Mayer theories.
Dependence of electrical conductivity on Bi₂Se₃ thin film thickness
(Institute for Single Crystals, 2017) Menshikova, S. I.; Rogacheva, E. I.; Sipatov, A. Yu.; Fedorov, A. G.
Effect of film thickness d on electrical conductivity σ of n-Bi₂Se₃ thin films (d = 25-420 nm) prepared by thermal evaporation in vacuum onto glass substrates was investigated. It was established that the electrical conductivity increases with increasing of the thin films thickness. The observed effect is explained as a manifestation of the classical size effect connected with diffuse scattering of electrons at the thin film interfaces. The experimental σ(d) dependence is satisfactorily described using the Fuchs-Sondheimer theory for the film thickness d > 60 nm. The specularity parameter and value of electrons mean free path are determined based of the experimental data.