Crystal structure of thin CaSi2 films grown by radiation-induced epitaxy

Kacyuba, Aleksey V.; Двуреченский, А. В.; Камаев, Г. Н.; Володин, В. А.; Krupin, A. Yu.

doi:10.1016/j.jcrysgro.2021.126080

Cited by 9 publications

(7 citation statements)

References 12 publications

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“…According to the theoretical consideration in [26], the observed peak at 418 cm -1 can be associated with vibrations of Si atoms in the plane of two-dimensional silicon layers intercalated with calcium (vibration mode (Si)). A slight discrepancy with a theoretical value of 413 cm -1 obtained in [26] for bulk CaSi 2 may be associated with the strains in the experimental structure or the size effect [23]. Peaks at 388 and 346 cm -1 , corresponding to vibrations of Si atoms outside the plane of twodimensional silicon layers, are not observed in our structures.…”

Section: ≈ Dcontrasting

confidence: 97%

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Synthesis of Epitaxial Structures with Two-Dimensional Si Layers Embedded in a CaF2 Dielectric Matrix

Zinovyev

Zinovieva²,

Володин³

et al. 2022

Jetp Lett.

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The possibility of fabricating two-dimensional Si layers on a CaF2/Si(111) film by molecular beam epitaxy is studied. The growth conditions, under which the regions of two-dimensional Si layers are formed, are found. Raman spectroscopy, transmission electron microscopy, photoluminescence, and electron paramagnetic resonance (EPR) studies have shown that regions of two-dimensional Si layers are formed in epitaxial structures prepared by the deposition of one to three biatomic Si layers on the CaF2/Si(111) film surface at a temperature of 550°С. The Raman spectra of these structures exhibit a narrow peak at 418 cm–1, which is due to light scattering on vibrations of Si atoms in the plane of a two-dimensional Si layer intercalated with calcium. The EPR spectra of multilayer structures with regions of two-dimensional Si layers embedded in CaF2 demonstrate an isotropic signal with an asymmetric Dyson shape and the g-factor $$g = 1.9992$$ under illumination. Consequently, this signal can be attributed to photoinduced conduction electrons in extended two-dimensional Si islands. These results may be useful for understanding the mechanisms of the formation of two-dimensional materials on CaF2/Si(111) substrates.

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Section: ≈ Dcontrasting

confidence: 97%

“…3, lines 1-3 and 5). The position of this peak coincides with the position of one of the three peaks in the Raman spectra (at 418, 388, and 346 cm -1 ) characteristic of CaSi 2 crystal layers [22][23][24]. The crystal lattice of bulk CaSi 2 includes two-dimensional Si layers intercalated with calcium [25,26].…”

Section: ≈ Dsupporting

confidence: 63%

Synthesis of Epitaxial Structures with Two-Dimensional Si Layers Embedded in a CaF2 Dielectric Matrix

Zinovyev

Zinovieva²,

Володин³

et al. 2022

Jetp Lett.

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“…2, сплошная линия 1), продемонстрировали особенности, характерные для кристаллических слоев CaSi 2 в 3R-модификации [6]. Для обоих типов структур, независимо от толщины структуры, наблюдаются три пика при 418, 388 и 346 см −1 , что является принципиальным отличием от работы [7] на облученных областях, наблюдается широкая полоса излучения с максимумом при 570 нм (рис. 3, кривая 1).…”

Section: результаты и обсуждениеunclassified

Атомная структура и оптические свойства слоев CaSi-=SUB=-2-=/SUB=-, выращенных на CaF-=SUB=-2-=/SUB=-/Si-подложках

Зиновьев¹,

Кацюба²,

Володин³

et al. 2021

Физика И Техника Полупроводников

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In this work, we study the growth features, as well as the structural and optical properties of CaSi2 layers formed in the process of successive deposition of Si and CaF2 on a Si (111) substrate with simultaneous irradiation with high energy electron beam. The Raman spectra recorded in the regions of the electron beam action showed peaks characteristic of crystalline CaSi2 layers. The study of the surface morphology of the grown structures demonstrated that, under the chosen synthesis conditions, the formation of CaSi2 layers during electron irradiation occurs according to a two-dimensional layer mechanism. The photoluminescence spectra measured in the region modified by the electron beam have significant differences from the spectra measured outside this region.

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“…Earlier, we proposed a method for CaSi 2 synthesis using electron beam irradiation during the growth of CaF 2 layers with molecular beam epitaxy (MBE) [ 19 , 24 , 25 ]. It was assumed that the formation of CaSi 2 occurs through the stimulated decomposition of CaF 2 into Ca and F [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

“…It was assumed that the formation of CaSi 2 occurs through the stimulated decomposition of CaF 2 into Ca and F [ 26 ]. Fluorine is desorbed from the surface, and remaining calcium atoms bind chemically with silicon atoms, which come from the Si substrate at sufficiently high temperatures (>300 °C) under electron irradiation [ 24 ]. Calcium silicide produced in this way is a nonhomogeneous three-dimensional material representing a triangular network of elongated crystallites protruding from the surface of the CaF 2 film by tens of nanometers.…”

Section: Introductionmentioning

confidence: 99%

Radiation-Stimulated Formation of Two-Dimensional Structures Based on Calcium Silicide

et al. 2022

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The formation of CaSi2 polycrystalline structures under the postgrowth electron irradiation of epitaxial CaF2/Si(111) films with embedded thin Si layers was studied. The dependence on the electron exposure time was investigated for two types of structures with different film thicknesses. The optimal conditions for the formation of two-dimensional CaSi2 structures were found. Raman spectra of the structures after a 1 min electron irradiation demonstrated only one pronounced peak corresponding to the vibrations of Si atoms in the plane of the calcium-intercalated two-dimensional Si layer. An increase in the exposure time resulted in the transition from two- to three-dimensional CaSi2 structures having more complex Raman spectra with additional peaks typical of bulk CaSi2 crystals. Based on the results of microscopic studies and transport measurements, a model explaining the observed effects was proposed.

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Crystal structure of thin CaSi2 films grown by radiation-induced epitaxy

Cited by 9 publications

References 12 publications

Synthesis of Epitaxial Structures with Two-Dimensional Si Layers Embedded in a CaF2 Dielectric Matrix

Synthesis of Epitaxial Structures with Two-Dimensional Si Layers Embedded in a CaF2 Dielectric Matrix

Атомная структура и оптические свойства слоев CaSi-=SUB=-2-=/SUB=-, выращенных на CaF-=SUB=-2-=/SUB=-/Si-подложках

Radiation-Stimulated Formation of Two-Dimensional Structures Based on Calcium Silicide

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