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В. О. Харченко, Д. О. Харченко, С. В. Кохан, В. В. Яновський, А. В. Дворниченко
«Формування нанорозмірних структур адсорбату у процесах конденсації з газової фази»
PACS numbers: 05.40.-a, 05.65.+b, 45.70.Qj, 65.80.-g, 81.16.Rf, 82.40.Ck, 82.40.Np
Dynamics of adsorbate-islands’ formation at condensation from gaseous phase is studied in the framework of the generalized approach based on reaction-diffusion models. As found, the stabilization of nanopatterns in such-class models is achieved by nonequilibrium chemical reactions responsible for formation of complexes. It is found that, during the system evolution, pattern-selection processes are realized. As shown, the possible oscillatory regimes for islands’ formation are realized at finite propagation speed related to nonzero relaxation time for the diffusion flux. An influence of internal multiplicative noise on the pattern-formation processes is studied. As shown, such noise at small intensities governs transitions between ordered thermodynamical dense and diluted phases. These phase transitions are characterized by an increase of fluctuations of the coverage field and correlation radius of spatial modulations. An influence of local change in surface temperature due to adsorption–desorption processes on the adsorbate-islands’ formation processes at condensation from gaseous phase is studied. As found, the thermal effects shrink the range of temperature and pressure, when pattern formation is possible. As shown considering statistical properties of surface structures, the transitions between ordered phases related to low- and high-density states are accompanied by a formation of adsorbate or vacancy islands. It is found that spherical adsorbate and vacancy islands are characterized by different distribution functions over their sizes for different symmetries of substrate lattices. As shown, depending on system control parameters, island size distributions can change their modality. The size of localized adsorbate/vacancy clusters can be characterized by nanometre scale, and the size of these islands can be controlled by both primary and secondary mechanisms of pattern formation. A generalized model for adsorbate-islands’ formation in multilayer systems is proposed by taking into account transference reactions between layers. As shown, in such a system, a cascade of first-order phase transitions is realized. The number of such phase transitions is defined through the number of layers.