The radiation-induced phenomena of CaSi₂ crystal growth were investigated, both directly during the epitaxial CaF₂ growth on Si (111) and film irradiation with fast electrons on Si (111) after its formation, while maintaining the specified film thickness, substrate temperature and radiation dose. Irradiation in the process of the epitaxial CaF₂ film growth leads to the formation of CaSi₂ nanowhiskers with an average size of 5 µm oriented along the direction . The electron irradiation of the formed film, under similar conditions, leads to the homogeneous nucleation of CaSi₂ crystals and their proliferation as inclusions in the CaF₂ film. It is shown that both approaches lead to the formation of CaSi₂ crystals of the 3R polymorph in the irradiated region of a 10 nm thick CaF₂ layer.

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.

Ultrashort pulsed laser annealing is an efficient technique for crystallizing amorphous semiconductors with the possibility to obtain polycrystalline films at low temperatures, below the melting point, through non-thermal processes. Here, a multilayer structure consisting of alternating amorphous silicon and germanium films was annealed by mid-infrared (1500 nm) ultrashort (70 fs) laser pulses under single-shot and multi-shot irradiation conditions. We investigate selective crystallization of ultrathin (3.5 nm) a-Ge non-hydrogenated films, which are promising for the generation of highly photostable nanodots. Based on Raman spectroscopy analysis, we demonstrate that, in contrast to thicker (above 10 nm) Ge films, explosive stress-induced crystallization is suppressed in such ultrathin systems and proceeds via thermal melting. This is likely due to the islet structure of ultrathin films, which results in the formation of nanopores at the Si-Ge interface and reduces stress confinement during ultrashort laser heating.

In this paper, we study the effects of GeSi quantum dot emission coupling with the collective modes in the linear chains of Si disk resonators positioned on an SiO₂ layer. The emission spectra as a function of the chain period and disk radius were investigated using micro-photoluminescence (micro-PL) spectroscopy. At optimal parameters of the disk chains, two narrow PL peaks, with quality factors of around 190 and 340, were observed in the range of the quantum dot emission. A numerical analysis of the mode composition allowed us to associate the observed peaks with two collective modes with different electric field polarization relative to the chain line. The theoretical study demonstrates the change of the far-field radiation pattern with increasing length of the disk chain. The intensive out-of-plane emission was explained by the appearance of the dipole mode contribution. The obtained results can be used for the development of Si-based near-infrared light sources.