A technique is proposed for the formation of epitaxial films of silicon carbide, gallium and aluminum nitrides on the surface of non-planar silicon parts. Using the technique, a GaN/AlN/SiC/Si heterostructure was grown on the surface of a silicon ring. The samples were studied by scanning electron microscopy, as well as raman and energy dispersive spectroscopy. It is shown that the preliminary deposition of a SiC layer on silicon by the atomic substitution method, in which (111) facets are inevitably being formed regardless of the local crystallographic orientation of the substrate surface, makes it possible to efficiently grow subsequent layers of III-nitrides of both wurtzite and sphalerite types on silicon parts.

The process of growth of a multicomponent crystal at elevated supersaturations, in cases where the classical approximation of the immobility of atomic steps becomes incorrect, has been studied. Analytical expressions are derived that describe the rate of advancement of an ensemble of steps on a crystalline surface. The crystal growth rate is determined via layer-by-layer and spiral mechanisms. It is shown that the rate can differ significantly from the predictions of the classical theory of crystal growth. The results can be used to optimize the growth processes of both bulk crystals and thick epitaxial films of various multicomponent compounds and, in particular, semiconductor compounds of groups A3B5 and A2B6.

The growth of InGaN layers on hybrid SiC/Si substrates with orientations (100), (110), and (111) by the HVPE method was studied at temperatures that wittingly exceed the temperature of InN decomposition onto nitrogen atoms and metallic In (1000C). On substrates with orientations (110) and (111), the formation of InGaN nanocrystals was observed. The shape and growth mechanisms of nanocrystals were investigated. It is shown that nanocrystals nucleate on the (111) surface only inside V-defects formed at the points where screw dislocations exit onto the surface. On the (110) surface, nanocrystals are formed only on pedestals that arise during the film growth. An explanation is given for the difference in the growth mechanisms of nanocrystals on substrates of different orientations.

В работе рассмотрена эволюция поверхности кристаллов и тонких пленок под воздействием потока частиц и механической нагрузки. Возникновение неустойчивости на плоской поверхности кристалла может быть вызвано наличием вакансий в объеме кристалла, которые диффундируют к поверхности кристалла или к микропорам в его объеме. Показано, что описанный эффект может вызывать появление шероховатости и волнистости на поверхности кристалла с характерными масштабами, определяемыми свойствами потока частиц. Получено аналитическое выражение для критерия возникновения неустойчивости и описаны различные последствия развития неустойчивости. Результаты могут быть использованы для оценки условий роста тонких пленок, при которых поверхность устойчива к возникновению шероховатости по вакансионному механизму. Также исследована эволюция микропор, содержащихся в объеме кристалла, под воздействием растягивающих механических напряжений.

The mechanical properties of composite coatings made of silicon carbide on graphite are studied for the first time. For the deposition of coatings, a new method of annealing the initial graphite was used, which was in contact with a silicon melt in an atmosphere of carbon monoxide.The samples were studied by nanoindentation and scanning electron microscopy. It is shown that the formed coating consists of a continuous film of monocrystalline silicon carbide lying on the surface, dendrites and crystalline druses, with roots going deep into the sample through a system of pores. It is shown that the coating significantly increases the mechanical characteristics of the graphite surface, including the microhardness.

В работе предложены теоретические модели для описания роста кристаллических тонких пленок многокомпонентных соединений из газовой фазы по механизмам Бартона - Кабреры - Франка и Чернова. Получены аналитические выражения для нахождения зависимости скорости роста таких пленок от условий роста, парциальных давлений различных компонентов и температуры. Полученные результаты могут быть использованы для оценки скорости роста различных многокомпонентных кристаллов и тонких пленок без проведения натурных экспериментов.

Abstract The possibility of growing bulk (more than 7 μm thick) epitaxial semipolar AlN films on Si(001) and hybrid SiC/Si(001) substrates without cracks has been investigated. It is found that an AlN layer grown on the Si substrate is extended, whereas an AlN layer grown on the hybrid SiC/Si substrate is compressed. The limiting (critical) thickness of the semipolar AlN layer on the Si(001) substrate is determined to be ~7.5 μm. When the film thickness exceeds this value, an ensemble of cracks is formed in the film, leading to its total cracking and exfoliation from the substrate. The semipolar epitaxial AlN films with a thickness of more than 40 μm are grown on hybrid SiC/Si substrates without cracking and exfoliation from the substrate.

The growth of a faceted pore in a crystal by the Burton–Cabrera–Frank mechanism under action of a mechanical tensile load is considered. The growth is determined by the diffusion of vacancies existing in a crystal to the terraces and steps on the pore surface. The expressions for the speed of movement of a single step and a group of parallel steps, and also for the dependence of the normal growth rate of a pore by the spiral mechanism under action of applied load have been found. It is shown that, in a certain range of low tensile loads, the rate has a quadratic dependence on the load, while the dependence is linear at high loads. The influence of impurities on the crystal fracture by the pore growth mechanism under consideration is discussed.

AbstractThe time evolution of the ensemble of micropores formed in the near-surface region of silicon during the growth of thin films of silicon carbide is studied by the method of atom substitution. SiC/Si samples are studied by scanning electron microscopy, ellipsometry, and confocal Raman microscopy. The formation of the porous layer involves several characteristic stages: the emergence of single pores, their growth with the formation of dendrite-like structures, and subsequent coalescence into a continuous layer. It is shown that the thickness of the porous layer at the initial stages of the growth is proportional to the cubic root of time. The possible mechanisms of pore formation are discussed and a theoretical model is proposed to describe the dependence of the average thickness of the porous layer on time. The model is in a good qualitative agreement with the experimental results.

A heterostructure consisting of three thick layers: AlN (thickness 0.72 μm), AlGaN (thickness 1.82 μm) and GaN (thickness 2.2 μm) was grown by the method of chloride hydride epitaxy on Si with a buffer layer of nano-SiC. The nano-SiC layer was obtained by the method of atomic substitution. The grown heterostructure was studied by scanning electron microscopy, back-reflected electron diffraction, energy dispersive analysis, and Raman scattering. Studies have shown that the use of nano-SiC/Si substrates makes it possible to grow III-V layers with a high growth rate (~ 66 μm/h) without cracks and with small residual elastic stresses (~ 160 MPa).

A three-layer heterostructure consisting of AlN (∼0.72 μm thick), AlGaN (∼ 1.82 μm thick), and GaN (∼2.2 μm thick) layers has been grown by hydride–chloride vapor phase epitaxy (HVPE) method on a Si substrate with a SiC buffer nanolayer. The heterostructure was studied using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and other techniques. The results showed that SiC/Si substrates can be used for growing films of III–V semiconductor compounds by HVPE at a high rate (~66 μm/h) free of cracks and with small residual elastic stresses (~160 MPa).

This article presents a brief review and original studies of the elastic-plastic properties of nanoscale and microscale thin films on substrates. Studies are conducted on the example of wide gap semiconductor films, which are extremely important for modern micro-and-optoelectronics, such as: gallium nitride, silicon carbide and gallium oxide grown on silicon substrates. The focus is on the effect of film nanoscale on methods for analyzing experimental nanoindentation results. In particular, methods for the analysis of two-layer nanoscale films, as well as films of anisotropic materials, are discussed. The dynamics of elastic stresses in the indenter area are analyzed by the Raman maps. The main methods for modeling the elastoplastic properties of films by quantum chemistry and molecular dynamics are considered.

AbstractA 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.

Разработан метод отделения и переноса эпитаксиальных гетероструктур GaN/AlN и AlN, выращенных на кремнии с буферным слоем карбида кремния, на подложки любых типов, основанный на химическом травлении. Гетероструктуры GaN/AlN/SiC толщиной 2.5 мкм и AlN/SiC толщиной 18 мкм отделены и перенесены на стеклянную подложку. Показано, что буферный слой карбида кремния на кремнии, выращенный методом замещения атомов, имеет развитую подповерхностную структуру, которая позволяет легко отделить пленку от подложки и способствует релаксации упругой энергии, вызванной различием в коэффициентах теплового расширения пленки и подложки. Показано, что после отделения плeнки от подложки кремния механические напряжения в плeнке практически полностью релаксировали. DOI: 10.21883/FTP.2017.03.44218.8368

A chemical-etching based method for separating GaN/AlN and AlN epitaxial heterostructures grown on silicon with a silicon-carbide buffer layer and transferring them to substrates of any type is developed. GaN/AlN/SiC and AlN/SiC heterostructures 2.5 μm and 18 μm thick, respectively, are separated and transferred to a glass substrate. It is shown that a silicon-carbide buffer layer on silicon, grown by the substitution method, has a developed subsurface structure which allows easy separation of the film from the substrate and promotes the relaxation of elastic energy caused by a difference in thermal-expansion coefficients of the film and substrate. It is shown that mechanical stresses in the film after its separation from the silicon substrate almost completely relaxed.

A new effect of the n-and p-type doping of the Si(100) substrate with a SiC film on the growth mechanism and structure of AlN and GaN epitaxial layers has been revealed. It has been experimentally shown that the mechanism of AlN and GaN layer growth on the surface of a SiC layer synthesized by substituting atoms on n- and p-Si substrates is fundamentally different. It has been found that semipolar AlN and GaN layers on the SiC/Si(100) surface grow in the epitaxial and polycrystalline structures on p-Si and n-Si substrates, respectively. A new method for synthesizing epitaxial semipolar AlN and GaN layers by chloride–hydride epitaxy on silicon substrates has been proposed.

In silver-ion-containing ion-exchange glasses subjected to a constant electric field and temperature, fractal silver structures arise under the surface facing the cathode. The growth of the structures is characterized by random branching and the absence of self-crossings: the main part of the fractal is in the glass, and some ends of the branches emerge on the surface. As a possible application of substrates with fractal structures thus prepared, the determination of their surface-enhanced Raman scattering activity using Rhodamine 6G dye is described.

We studied the influence of hydrogen-reducible metal ions concentration profile under the surface of ion exchanged glass on the behavior of the layered glass-metal nanocomposite which can be formed via self-arranging in the course of thermal processing of the glass in hydrogen atmosphere. The modeling shows that depending of the ascending or descending type of the concentration profile the layered nanocomposite with decreasing or increasing gaps between the layers of nanoparticles can be formed. In certain cases the mean radius and the particle size-distribution function may be the same among the subsequent layers. A proper choice of the ascending concentration profile can provide practically equidistant layers of the nanocomposite applicable for photonic crystals and Bragg gratings.

A rigorous system of equations describing the formation and growth of metallic nanoparticles in a reductant-containing glass upon introduction of reduced metal ions by ion exchange into the glass has been formulated and solved numerically. The influence of the system parameters on the process of nanoparticle growth has been analyzed. The obtained dependences of the distributions of the particle radii and concentrations in the bulk of the glass agree well with the available experimental data.