[en] To crystallize hydrogenated amorphous silicon films on glass substrates, pulsed Ti-sapphire laser radiation is used, with a pulse duration less than 30 fs. The initial films are grown by plasma-enhanced chemical-vapor deposition at the temperatures 200 and 250°C. The structural properties of the initial films and films treated with laser radiation pulses are studied by Raman spectroscopy. The conditions for complete crystallization of the films grown on glass substrates to thicknesses of up to 100 nm and hydrogen content of up to 20 at % are established. The conditions provide the fabrication of highly homogeneous films by scanning laser treatments. It is found that, if the hydrogen content in the film is 30–40 at %, the crystallization is an inhomogeneous process and laser ablation is observed in some areas of the films.

[en] The technique of Raman spectroscopy has been used to investigate doped (n-type) and undoped GaAs/AlAs superlattices with AlAs barrier thicknesses from 17 to 1 monolayers. The peak corresponding to the scattering by a two-dimensional plasmon was found in the Raman spectrum of a doped superlattice with relatively thick barriers. The position of the experimental peak corresponded to the value calculated in the model of plasma oscillations in periodic planes of a two-dimensional electron gas. The electron tunneling effects played an increasingly prominent role as the AlAs barrier thickness decreased. The peaks corresponding to the scattering by coupled phonons with three-dimensional plasmons were found in the Raman spectra for a superlattice with an AlAs thickness of 2 monolayers; i.e., the delocalization of coupled modes was observed. In this case, the folding of acoustic phonons was observed in the superlattice under consideration, indicative of its good periodicity, while the localization of optical phonons in GaAs layers was observed in undoped superlattices with an AlAs thickness of 2 monolayers

[en] The nucleation of the crystalline Ge phase in SiO_xN_y films implanted with Ge⁺ ions with the energy 55 keV to doses of 2.1 × 10¹⁵–1.7 × 10¹⁶ cm^–2 and then annealed at a temperature of T_a = 800–1300°C under pressures of 1 bar and 1–12 kbar is studied. From analysis of the Raman spectra, it is concluded that amorphous Ge precipitates increase in size upon hydrostatic compression at a temperature of 1000°C. Raman scattering at optical phonons localized in Ge nanocrystals is observed only after annealing of the samples with the highest content of implanted atoms at a temperature of 1300°C. In the photoluminescence spectra, a peak is observed at the wavelength ∼730 nm. The peak is considered to be the manifestation of the quantum-confinement effect in nanocrystals ∼3 nm in size.

[en] The Raman spectra of SiO₂ films containing InSb spherical nanocrystals produced by ion-beam synthesis are studied. TO- and LO-like modes in the spectra of the InSb nanocrystals are detected at frequencies of 187 and 195 cm^–1, respectively. The shift of these modes to high frequencies with respect to the corresponding frequencies in InSb bulk crystals is analyzed from the viewpoint of the influence of the quantum-confinement effect, strains in nanocrystals, the surface phonon frequency, and scattering at the frequency corresponding to stretched anion–cation modes at the surface of polar spherical nanocrystals. The position of the 195-cm^–1 mode corresponds to LO phonons in InSb nanocrystals hydrostatically compressed in the SiO₂ matrix at pressures of about 10 kbar. The 187-cm^–1 mode corresponds to resonance at the Fröhlich frequency.

[en] Raman spectroscopy is used to monitor the composition and strains of Ge_xSi_1-x alloy films with 0.17 ≤ x ≤ 1.0. The composition and strains in the films were also determined from the X-ray diffraction data. Both the position and intensity of the Raman peaks related to vibrations of the Ge-Ge, Ge-Si, and Si-Si bonds were analyzed. This analysis provided substantial refinement of certain model parameters for calculation of the composition and strains in Ge_xSi_1-x/Si(100) heterostructures on the basis of Raman spectroscopy data

[en] Raman spectra of films of nearly stoichiometric amorphous silicon nitride (a-Si₃N₄) reveal a contribution due to local oscillations of silicon–silicon (Si–Si) bonds. This observation directly confirms that the almost stoichiometric a-Si₃N₄ contains Si–Si bonds, which, according to theoretical predictions, act as electron and hole traps that are responsible for the memory effect in Si₃N₄.

[en] Decomposition of germanium monoxide (GeO) films under the impact of an atomic force microscope (AFM) tip was observed for the first time. It is known that GeO is metastable in the solid phase and decomposes into Ge and GeO₂ under thermal annealing or radiation impact. AFM tip treatments allow us to carry out local decomposition. A novel tip-induced local electrical decomposition (TILED) method of metastable GeO films has been developed. Using TILED of 10 nm thin GeO film, Ge nanowires on silicon substrates were obtained

[en] The effect of high-power nanosecond (20 ns) and femtosecond (120 fs) laser pulses on silicon nanostructures produced by ion-beam-assisted synthesis in SiO₂ layers or by deposition onto glassy substrates is studied. Nanosecond annealing brings about a photoluminescence band at about 500 mn, with the intensity increasing with the energy and number of laser pulses. The source of the emission is thought to be the clusters of Si atoms segregated from the oxide. In addition, the nanosecond pulses allow crystallization of amorphous silicon nanoprecipitates in SiO₂. Heavy doping promotes crystallization. The duration of femtosecond pulses is too short for excess Si to be segregated from SiO₂. At the same time, such short pulses induce crystallization of Thin a-Si films on glassy substrates. The energy region in which crystallization is observed for both types of pulses allows short-term melting of the surface layer

[en] The procedure of determining the composition and mechanical strains in Ge_xSi_1-x quantum dots with the use of Raman spectroscopy is substantially refined. The parameter x characterizing the composition is determined by analyzing the intensity of the peaks in the Raman spectra that correspond to the Ge-Ge and Ge-Si bond vibrations, taking into account the Ge-Si bonds at the heterointerface. The strains in the quantum dots are determined by analyzing the position of the Raman peaks, taking into account the data obtained for the composition of the quantum dots

[en] The effect of high-power nanosecond (20 ns) and femtosecond (120 fs) laser pulses on silicon nanostructures produced by ion-beam-assisted synthesis in SiO₂ layers or by deposition onto glassy substrates is studied. Nanosecond annealing brings about a photoluminescence band at about 500 mn, with the intensity increasing with the energy and number of laser pulses. The source of the emission is thought to be the clusters of Si atoms segregated from the oxide. In addition, the nanosecond pulses allow crystallization of amorphous silicon nanoprecipitates in SiO₂. Heavy doping promotes crystallization. The duration of femtosecond pulses is too short for excess Si to be segregated from SiO₂. At the same time, such short pulses induce crystallization of Thin a-Si films on glassy substrates. The energy region in which crystallization is observed for both types of pulses allows short-term melting of the surface layer.