Выполнен симметрийный анализ кристаллической структуры и фононного спектра в процессе непрерывного превращения кремния в карбид кремния. Определена трансформация симметрии фононов в точках высокой симметрии зоны Бриллюэна при переходе от исходной кубической структуры кремния (алмаза) через промежуточную кубическую структуру SiC к тригональной структуре SiC. Установлены правила отбора для ИК и рамановских спектров во всех трех фазах. Авторы благодарят за финансовую поддержку РФФИ (гранты N 15-0306155 и 16-29-03149 -офи-м). DOI: 10.21883/FTT.2017.01.43946.267
A new trigonal (rhombohedral) SiC phase, existence of which was previously theoretically predicted by a symmetry analysis, is studied. It is shown that the phase can be formed during the growth of SiC films by the method of substitution of atoms on the surface of a Si substrate. Ab initio calculations of the crystal structure of a new phase and its Raman spectra are performed by the quantum chemistry method. The difference of the selection rules for the Raman active vibrations for this rhombohedral phase from the selection rules for a cubic phase in the coordinate system aligned with the translation vectors of the rhombohedral phase is established. Series of thin SiC/Si films by annealing time are synthesized by the method of the topochemical substitution of atoms, and their Raman spectra are analyzed. The presence of the spectral line (258 cm^–1), that is close to the line of a new trigonal (rhombohedral) phase calculated by the ab initio method, has been found in the Raman spectra of the samples at the initial stage of the growth of a SiC film, which indirectly confirms its existence.
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