Простой метод изготовления нанопроволок карбида кремния

In this work, we introduce a simple and convenient approach for growing SiC nanowires (SiCNWs) directly on carbon source from graphite. The commercial SiO powder and the cheap common graphite were used as the source materials. SiCNWs have been synthesized during holding time less than 60-80 min at 1450-1500 C by using a simple and low-cost method in an industrial furnace with a resistant heater.У даній роботі представлено простий і зручний підхід для вирощування нанодротів карбіду кремнію (SiCNWs) безпосередньо на джерело вуглецю з графіту. У якості вихідних матеріалів були використані промисловий порошок SiO і дешевий звичайний графіт. SiCNWs були синтезовані за допомогою простого і недорогого методу під час витримки в промисловій печі зі стійкими нагрівачем 60-80 хв при температурі 1450-1500 С.В данной работе представлен простой и удобный подход для выращивания нанопроволок карбида кремния (SiCNWs) непосредственно на источнике углерода из графита. В качестве исходных материалов были использованы промышленный порошок SiO и дешевый обычный графит. SiCNWs были синтезированы с помощью простого и недорогого метода во время выдержки в промышленной печи с устойчивыми нагревателем 60-80 мин при температуре 1450-1500 С

Drift correction of the analyzed area during the study of the lateral elemental composition distribution in single semiconductor nanostructures by scanning Auger microscopy

The main difficulty in obtaining the lateral elemental composition distribution maps of the semiconductor nanostructures by Scanning Auger Microscopy is the thermal drift of the analyzed area, arising from its local heating with the electron probe and subsequent shift. Therefore, the main goal of the study was the development of the effective thermal drift correction procedure. The measurements were carried out on GeSi/Si nanoislands obtained with molecular beam epitaxy by means of Ge deposition on Si(100) substrate. Use of the thermal drift correction procedure made it possible to get the lateral elemental composition distribution maps of Si and Ge for various types of GeSi/Si nanoislands. The presence of the germanium core and silicon shell in both the dome GeSi/Si nanoislands and pyramid ones was established. In the authors’ opinion, this type of elemental distribution is a result of the completeness of the interdiffusion processes course in the island/wetting layer/substrate system, which play the key role in the nucleation, evolution and growth of GeSi/Si nanoislands. The proposed procedure of the thermal drift correction of the analyzed area allows direct determination of the lateral composition distribution of the GeSi/Si nanoislands with the size of the structural elements down to 10 nm

Theoretical and experimental study of Raman scattering in mixed (MoS₂)x(MoSe₂)₁₋x layered crystals

Raman scattering in mixed MoS₂/MoSe₂ layer type crystals was investigated in this work. The change of intensities and positions of bands for in-plane E¹₂g and outof-plane A₁g vibrations as functions of the “concentration” inherent to corresponding type layers has been studied. Estimation of interlayer interaction was obtained from comparison of experiment and theory, and effect of this interaction on the frequency of intralayer phonon was studied

Simple method for SiC nanowires fabrication

In this work, we introduce a simple and convenient approach for growing SiC nanowires (SiCNWs) directly on carbon source from graphite. The commercial SiO powder and the cheap common graphite were used as the source materials. SiCNWs have been synthesized during holding time less than 60-80 min at 1450-1500 °C by using a simple and low-cost method in an industrial furnace with a resistant heater

Biomorphous SiC ceramics prepared from cork oak as precursor

Porous ceramic materials of SiC were synthesized from carbon matrices obtained via pyrolysis of natural cork as precursor. We propose a method for the fabrication of complex-shaped porous ceramic hardware consisting of separate parts prepared from natural cork. It is demonstrated that the thickness of the carbon-matrix walls can be increased through their impregnation with Bakelite phenolic glue solution followed by pyrolysis. This decreases the material's porosity and can be used as a way to modify its mechanical and thermal characteristics. Both the carbon matrices (resulted from the pyrolysis step) and the resultant SiC ceramics are shown to be pseudomorphous to the structure of initial cork. Depending on the synthesis temperature, 3C-SiC, 6H-SiC, or a mixture of these polytypes, could be obtained. By varying the mass ratio of initial carbon and silicon components, stoichiometric SiC or SiC:C:Si, SiC:C, and SiC:Si ceramics could be produced. The structure, as well as chemical and phase composition of the prepared materials were studied by means of Raman spectroscopy and scanning electron microscopy

Efficient core-SiO₂/shell-Au nanostructures for surface enhanced Raman scattering

The efficient SERS (surface enhanced Raman scattering) substrates that are films of nanoparticles (NP) of the “core–shell” type, where the core of SiO2, and the shell of gold nanoparticles, were developed in this work. Application of scanning electron microscopy and optical absorption enabled to find correlation between surface morphology of nanostructures and position of the plasmon absorption band. It helped to adjust the latter to the wavelength of exciting laser radiation. It has been shown that the designed nanostructures are able to enhance electric field of an emitting dipole not only due to adjustment of the band frequency for plasmon absorption to the wavelength of exciting laser radiation but also due to contribution of the so-called “hot spots” to enhancement of electric field scattering. Analysis of characteristics inherent to SERS substrates with nanostructures of the soil core – Au shell type has shown that they enhance the Raman signal by 5 orders higher as compared with the substrates based on SiO2 nanospheres not covered with gold nanoparticles

Paramagnetic defects related to photoluminescence in SiOx films

The correlation between the photoluminescence and paramagnetic defects is studied in SiOx films grown by vacuum thermal deposition and annealed at 750 ⁰C. The as-grown samples exhibit a wide structureless EPR line centered at g = 2.0040, which is explained by the presence of a variety of dangling bonds •Si = SiyO₃–y. The annealing at 750 ⁰C causes the formation of amorphous silicon inclusions in SiOx matrix, appearance of the photoluminescence peaked at ~ 1.8 eV and shift of the EPR line to the low field range. The latter implies the preferable annealing of the paramagnetic defects in the regions of the sample with higher concentration of oxygen. The optically detected magnetic resonance studies show that these defects are not responsible for the luminescence; they are the centers of nonradiative recombination, but the efficiency of photoluminescence quenching due to these defects is rather low

Obtaining and optical properties of the glasses of the GeS₂–HgS system

The glassy alloys of the GeS₂–HgS system in the range of 0–50 mol. % HgS were obtained by the melt quenching technique. Their Raman spectra were investigated. The dependence of the particularities of the light scattering bands on the chemical composition was analyzed

Effect of Si infiltration method on the properties of biomorphous SiC

Two types of wood-based biomorphous SiC composites with different microstructure were obtained by infiltration of carbon template with liquid or vapour silicon. The oak, pine, lilac, walnut, acacia woods available in Ukraine were used as the biological template in this work. SEM, optical and AFM data indicated that biomorphous SiC obtained by melt infiltration consists of crystalline phase of 3C-SiC, while that of vapor infiltration results in formation of crystalline and amorphous phases of 3C-SiC. The same results were obtained for infiltration of carbon fibers. Thus, it was suggested that the mechanism of SiC formation is governed by the infiltration method

Nanostructured silver substrates with stable and universal sers properties: Application to organic molecules and semiconductor nanoparticles

Nanostructured silver films have been prepared by thermal deposition on silicon, and their properties as SERS substrates investigated. The optimal conditions of the post-growth annealing of the substrates were established. Atomic force microscopy study revealed that the silver films with relatively dense and homogeneous arrays of 60-80-nm high pyramidal nanoislands are the most efficient for SERS of both organic dye and inorganic nanoparticles analytes. The noticeable enhancement of the Raman signal from colloidal nanoparticles with the help of silver island films is reported for the first time. © 2009 The Author(s)