Обсуждаются механизмы образования, кристаллическая структура, особенности дефектообразования и состав формируемой при пониженных (менее 900 °С) ростовых температурах на поверхности Si из углеводорода и гидридов сплошной карбидной пленки. Показано, что при выращивании в течение длительного времени толстых карбидных слоев под карбидным слоем образуется система макродефектов и подстилающая поверхность, подобная пористому кремнию. Присутствие переходного слоя твердого раствора между карбидным слоем и подложкой из кремния проявляется в положении линий люминесцентных спектров исследуемых структур в области ближнего ИК диапазона. Для установления наиболее вероятных механизмов наблюдаемых излучательных переходов проведен анализ температурного поведения спектральных линий и расчет характера распределения по слоям структуры возбуждаемых светом неравновесных носителей заряда.

AbstractThe effect of boron implantation on the light-emitting properties of dislocation structures formed in silicon by Si^+ ion implantation with subsequent annealing is studied. It is shown that the implantation of B^+ ions has a significant effect on the dislocation-related luminescence intensity, spectrum and the temperature dependence of the D1-band intensity. It is found that the temperature dependence is nonmonotonous and involves two regions, in which the D1-band intensity increases with increasing temperature and has two well-pronounced maxima at 20 K and 60–70 K. The maximum at 20 K is associated with the morphological features of the dislocation structure under study, whereas the maximum at 60–70 K is associated with the additional implantation of the boron impurity into the dislocation region of the samples. It is established that the intensities of the experimentally observed maxima and the position of the high-temperature maximum depend on the implanted boron concentration.

A method of synthesizing carbon films on single-crystal silicon substrates by methane pyrolysis in an electrical field is suggested. The pressure and temperature arising in a working chamber when the substrate is exposed to C–4 ions during pyrolysis are measured. Ion bombardment generates nuclei in the form of fibers about 2 μm in diameter providing the growth of a polycrystalline film. The resulting material is examined using electron microscopy and photo- and cathodoluminescence. Synthesized films are a composite material the matrix of which contains nanoclusters of a dissimilar crystalline nature. The effect of considerable two-stage decrease in the resistivity of the film material with increasing temperature from 300 to 1750 K is discovered. This points to the semiconducting properties of thick carbon films.

Comprehensive studies of the structure and electronic properties of defects occurring on the connection boundary of disarranged n − type Si(001) wafers have been made by the methods of transmission electron microscopy, deep level transient spectroscopy (DLTS) and photoluminescence. The main revealed defects are two types of dislocation structure: orthogonal dislocation network composed of two screw dislocation families and zigzag mixed dislocations. The dislocation structures observed are sources of intense luminescence whose spectra are appreciably different from the standard dislocation luminescence spectra at all the investigated misfit angles of the Si bonded wafers. We show that an increase of the misfit angle results in a strong transformation of the dislocation luminescence spectra consisting in changes of the form of the spectra and a decrease in the integral luminescence intensity. In the samples in question the DLTS method revealed the presence of deep centers the concentration of which increased with increasing of twist misorientation of bonded wafers. It has been established that the deep centers are related to the dislocation structures observed by means of transmission electron microscopy.

In the work the properties of grain-oriented layers of the cubic phase of silicon carbide and SiGeC nanoscale basic region formed under them at the inner boundary of the 3C-SiC/SiGeC/Si(100) heterojunction are discussed. The structures are obtained in the process of low-temperature (below 1000 °C) carbidization of the silicon surface in vacuum with the use of molecular beams of hydrides and hydrocarbons. The main attention is focused on the discussion of the composition, microstructure, and surface morphology of the layers. The light-emitting properties of the structures in the band-edge photoluminescence from silicon are studied. The diode characteristics of the heterojunction are also studied. Mathematical modeling methods are employed to investigate the band structure of the heterojunction under different injection level conditions of non-equilibrium charge carriers to the basic region of the system.

Парамагнитные дефекты нового типа с концентрацией порядка 10 15 см -3 генерируются при пластическом деформировании изотопно-обогащенных кристаллов 29Si (72%, 76%) при температуре 950 °С. Спектры электронного парамагнитного резонанса (ЭПР) этих дефектов анизотропны и обладают значительной шириной (до 1 кЭ). Неоднородное уширение линий ЭПР обусловлено вариациями внутреннего магнитного поля в скоррелированных кластерах дефектов. Спектры ядерного магнитного резонанса (ЯМР) в деформированных кристаллах представляют собой дублеты Пейка, расщепленные спин-спиновым ядерным взаимодействием. Уширение спектров ЯМР вызвано ядерной диполь-дипольной релаксацией.

The distribution profiles of the dopant in the surface layer of a SiO2/Si structure implanted with Zn and O ions are studied via Rutherford backscattering spectroscopy for He2+ ions using the channeling technique. The redistribution of implanted impurities in the Si surface layer during the formation process of zinc oxide (ZnO) nanoparticles is analyzed. The effect of the annealing temperature on the formation process and growth of ZnO nanoparticles is studied. The sample-surface morphology is examined via atomic force microscopy. The optical absorption and photoluminescence of the implanted layers are studied.

Paramagnetic defects of a new type with a concentration of about 1015 cm−3 are shown to be generated during the plastic deformation of isotope-rich (72%, 76% 29Si) silicon crystals at a temperature of 950°C. The electron paramagnetic resonance (EPR) spectra of these defects are anisotropic and have a significant width (up to 1 kOe). The nonuniform broadening of the EPR lines is caused by the variation of the internal magnetic field in correlated defect clusters. The nuclear magnetic resonance (NMR) spectra of the deformed crystals consist of Pake doublets split by nuclear spin-spin interaction. The broadening of the NMR spectra is caused by nuclear dipole-dipole relaxation.

Synthesis, morphology, and structural characteristics of carbon and SiC/C nanocomposites with a lattice of inverse opal were investigated. Porous structure characteristics were determined by gas adsorption-desorption. Photoluminescence of SiC/C nanocomposites, induced by implantation of helium ions, and their structure revealed by high-resolution transmission electron microscopy were studied.

The light-emitting properties of cubic silicon carbide films grown by vacuum vapor phase epitaxy on Si(100) and Si(111) substrates under conditions of decreased growth temperatures ( T gr ∼ 900–700°C) have been discussed. Structural investigations have revealed a nanocrystalline structure and, simultaneously, a homogeneity of the phase composition of the grown 3 C -SiC films. Photoluminescence spectra of these structures under excitation of the electronic subsystem by a helium-cadmium laser (λ excit = 325 nm) are characterized by a rather intense luminescence band with the maximum shifted toward the ultraviolet (∼3 eV) region of the spectral range. It has been found that the integral curve of photoluminescence at low temperatures of measurements is split into a set of Lorentzian components. The correlation between these components and the specific features of the crystal structure of the grown silicon carbide layers has been analyzed.

Highly porous periodic structures consisting of a three-dimensional replica of pores in the initial opal lattice have been synthesized by high-temperature thermochemical treatment of opal matrices filled with carbon compounds, followed by dissolution of silicon dioxide. It has been shown that the main phases of the composite are carbon and silicon carbide. Based on the X-ray diffraction, Raman, and IR spectroscopy data, it has been assumed that the composite contains fragments of hexagonal diamond. The photoluminescence and optical reflection spectra of the composites have been measured.

The light-emitting properties of cubic-lattice silicon carbide SiC films grown on Si(100) and Si(111) substrates with VPE at low temperatures (T gr ∼ 700°C) are discussed. Investigations of the grown films reveal a homogeneous nanocrystalline structure involving only the 3C-SiC phase. When the electron subsystem of the structure is excited by a He-Cd laser emitting at λexit = 325 nm, the photoluminescence (PL) spectra contain a rather strong emission band shifted by about 3 eV toward a short-wave spectral region. At low temperatures, the PL integral curve is split into a set of Lorentz components. The relation between these components and the peculiarities of the energy spectrum of electrons in the nanocrystalline grains of the silicon carbide layers is discussed.

The conditions for synthesizing an opal-zirconia-carbon nanocomposite in the form of monolithic (without pores) transparent silica with an ordered distribution of nanocrystals throughout the sample have been determined. Zirconia nanocrystals form a three-dimensional periodic lattice of nanoclusters with sizes ranging from several nanometers to several tens of nanometers. This nanocomposite exhibits properties typical of photonic crystals. The samples have been studied using electron microscopy, X-ray diffraction, photoluminescence, and Raman scattering. The structural state and spatial arrangement of zirconia nanocrystals and carbon clusters in the nanocomposite have been elucidated. Optical transmission and optical reflection photoluminescence spectra of the nanocomposites have been measured.

The influence of high-temperature treatment of opal—erbium composites on their spectral properties in the wavelength region of 1.5 μm is investigated, the dependence of the luminescence intensity on the erbium concentration is measured, and the structure of the composite after high-temperature treatment is examined using transmission electron microscopy. The regular structure of the composites undergoes considerable transformations up to the complete loss of periodicity upon annealing at a temperature of 1500 K for 10 h and more. The composites in this case are sintered into a homogeneous substance. Pores disappear, and erbium oxide inclusions in the form of 30- to 70-nm regular solid spheres are observed instead. Measurements of the luminescence spectra in the wavelength region of 1.5 μm for the opal-erbium composites with erbium oxide concentrations in the range 0.25–16.00 wt % have shown that the luminescence yield reaches the maximum at an Er 2 O 3 content of 1 wt % in the composite. Analysis of the influence of the temperature and time of heat treatment on the luminescence intensity of the samples has revealed a nonmonotonic character of the dependence on the annealing time for all the temperatures under investigation. The factors responsible for this behavior are discussed. The reflection spectra of the opal-Er 2 O 3 (1 wt %) composites after heat treatment have demonstrated that the photonic band gap of the samples degrades at annealing temperatures of 1300 K and higher. A method proposed for retaining the periodic structure upon heat treatment consists in introducing the stabilizing phase into the opal.