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Документ Surface morphology of nanostructured gas sensors based on metal-polymer compounds(Kamianets-Podіlskyi National Ivan Ohiienko University, 2020) Harbuz, D. O.; Pospelov, A. P.; Romanov, M. D.; Mateychenko, P. V.; Konotop, A. P.; Gudimenko, V. A.; Kamarchuk, G. V.Документ Growth and Structural Characterization of Thermally Evaporated Topological Insulator Bi2Se3 Thin Films(NanoCOFC, 2018) Rogachova, E. I.; Fedorov, A. G.; Krivonogov, S. I.; Mateychenko, P. V.; Dobrotvorskaya, M. V.; Garbuz, Alexander G.; Sipatov, A. Yu.Публікація Percolation transition and physical properties of Bi1-xSbx solid solutions at low Bi concentration(Elsevier Ltd, 2020) Rogacheva, E. I.; Doroshenko, A. N.; Khramova, T. I.; Nashchekina, O. N.; Fedorov, A. G.; Mateychenko, P. V.The dependences of microhardness H, electrical conductivity σ, charge carrier mobility μH, the Seebeck coefficient S, and thermoelectric power factor P = S2σ on the composition of Bi1-xSbx solid solutions in the vicinity of pure Sb (x = 1.0–0.975) were obtained. In the range of x = 0.9925–0.9875, an anomalous decrease in H and S and increase in σ and μH with increasing Bi concentration were observed. For all the alloys, the dependences of H on the load on an indenter G were plotted. It was found that the H(G) dependences for samples with x smaller than ~ 0.99 and for samples with x exceeding 0.99, exhibit different behavior. The results obtained are interpreted on the basis of our assumption about the existence of a percolation-type phase transition from impurity discontinuum to impurity continuum that occurs in any solid solution.Публікація Growth and structure of thermally evaporated Bi2Te3 thin films(Elsevier, 2016) Rogacheva, E. I.; Budnik, A. V.; Dobrotvorskaya, M. V.; Fedorov, A. G.; Krivonogov, S. I.; Mateychenko, P. V.; Nashchekina, O. N.; Sipatov, A. Yu.The growth mechanism, microstructure, and crystal structure of the polycrystalline nBi2Te3 thin films with thicknesses d = 15 – 350 nm, prepared by thermal evaporation in vacuum onto glass substrates, were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi2Te3. It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from [00l] to [015] under increasing d. The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5 – 2.0 nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n-Bi2Te3 thin films of a sufficiently high quality.Публікація Structure of thermally evaporated bismuth selenide thin films(Науково-технологічний комплекс "Інститут монокристалів", 2018) Rogacheva, E. I.; Fedorov, A. G.; Krivonogov, S. I.; Mateychenko, P. V.; Dobrotvorskay, M. V.; Garbuz, A. S.; Nashchekina, O. N.; Sipatov, A. Yu.The Bi₂Se₃ thin films with thicknesses d = 7-420 nm were grown by thermal evaporation in vacuum of stoichiometric n-Bi₂Se₃ crystals onto heated glass substrates under optimal technological conditions determined by the authors. The growth mechanism, microstructure, and crystal structure of the prepared thin films were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. It was established that the prepared thin films were polycrystalline, with composition close to the stoichiometric one, did not contain any phases apart from Bi₂Se₃, were of a high structural quality, and the preferential growth direction [001] corresponded to the direction of a trigonal axis C₃ in a hexagonal lattice. The films, like the initial crystal, exhibited n-type conductivity. It was shown that with increasing film thickness, the grain size and the film roughness remain practically the same at thicknesses d < 100 nm, and after that increase, reaching their saturation values at d ~ 300 nm. It follows from the results obtained in this work that using the method of thermal evaporation in vacuum from a single source, one can prepare thin n-Bi₂Se₃ films of a sufficiently high structural quality with a composition close to the stoichiometric one and the preferential growth orientation.Документ Structure of p-Bi₂Te₃ thin films prepared by single source thermal evaporation in vacuum(2015) Rogacheva, E. I.; Budnik, A. V.; Fedorov, A. G.; Krivonogov, A. S.; Mateychenko, P. V.The growth mechanism, microstructure, and crystal structure of thin Bi₂Te₃ films with thicknesses d = 28 - 620 nm prepared by thermal evaporation of stoichiometric Bi₂Te₃ crystals in vacuum onto glass substrates were studied using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy. The obtained thin films were polycrystalline, exhibited p-type conductivity and did not contain any other phases except for Bi₂Te₃. It was shown that with increasing film thickness, the crystallite size increased up to ~ 700-800 nm. It was established that the preferential orientation of crystallite growth was [00l] direction corresponding to a trigonal axis С3 in hexagonal lattice. When the film thickness exceeded ~ 200-250 nm, along with reflections from (00l) planes, reflections from other planes appeared, which indicated a certain disorientation of crystallites. The results obtained show that using a simple and inexpensive method of thermal evaporation from a single source and choosing optimal technological parameters, one can grow thin p-Bi₂Te₃ films of sufficiently high quality.