Papers by Keyword: Silicon

Abstract: Nanometer-scale protuberance and groove processing was performed on a silicon (Si) surface by diamond tip sliding using atomic force microscopy (AFM). The protuberances of 0-5 nm height were obtained the silicon surface by using the diamond tip of approximately 200 nm radius and the grooves of 0-2 nm depth were processed by the tip of about 50 nm radius. It was observed that both protuberance and groove were produced using the tip of about 100 nm radius. Indentation measurements show the hardness of processed parts was greater than that of unprocessed parts. Potassium hydroxide (KOH) solution etching was performed on the mechanochemically processed sample. The processed areas were prevented from etching due to the formation of a dense oxide layer. This may be because the processed parts were oxidized by tip sliding due to the effect of mechanochemical oxidation.

Abstract: Additions of grain refiners based on Ca, Ca/Si, Al3Ti and Al4C3 to pure magnesium and AZ31 alloy result in remarkable microstructure refinement. With proper amount of these refiners addition, the grain size in as-cast ingots is one order of magnitude lower than that without refiner addition. Small amount of refiner addition to alloy AZ31 increases both ultimate and yield strength significantly, and the ductility of the alloy is similar to that without refiner addition. Additions of refiner improve the deformation formability of the AZ31 alloy.The extruded and hot rolled specimens (rods or sheets) with refiner addition are crack free and exhibit higher surface quality and mechanical properties than that without refiner addition.

Abstract: The fabrication process and the spectral properties of gratings for the infrared wavelength region on the basis of 3C-SiC layers grown by CVD on (100) oriented Si substrates are demonstrated. The formed 3C-SiC gratings on Si support two phonon polaritons as a function of the geometrical properties excited between 10.3 and 11.4 µm. They appear as a dip in the transmission spectrum. A third minimum in the transmission spectrum is caused by the substrate – grating interaction. The obtained resonances were polarization sensitive, i.e. they appeared only under TMpolarized illumination.

Abstract: Solid source molecular beam epitaxy was applied to create silicon carbide nanoclusters on silicon. The island size distribution can be controlled by an appropriate substrate temperature, carbon fluxes and process times. Rate equation computer simulation was applied to simulate the experimental obtained nano scale nuclei properties.

Abstract: A comparison study of radiation damage in n-type silicon grown by the floating zone technique and n-type silicon carbide grown by the sublimation epitaxy technique was carried out for the first time under the same irradiation conditions. This comparison is drawn for an energy region of fast electrons at ≈ 1 MeV where Frenkel pairs as primary defects, i e the self-interstials bound to their parent vacant sites at a distance of a few lattice spacings, are produced most effectively. The removal rates of charge carriers in n-Si and n-SiC (4H and 6H) were found to be about 0.23 cm-1 and 0.015 cm-1, respectively. The possible reasons of the observed difference are briefly discussed.

Abstract: The results of direct kinetic measurements and SEM observations on formation of silicide phases in Mo-Si system at temperatures 1400-1700о С are presented in the work. It was shown, that the formation of MoSi2 proceeds by two different mechanisms and accordingly, two types of microstructures are formed: (i) a compact layer (usually with expressed columnar structure) by the reaction diffusion mechanism; and (ii) separated fine grains by crystallization in the volume of saturated Me-Si melt. A model of product formation is offered which allows to calculate the relative contributions of the two mechanisms of disilicide phase formation at various stages of interaction and to estimate the role each of them in the total process.

Abstract: In this paper we discuss possible mechanisms of PV annealing in Si. Our approach includes a combination of density functional theory and lattice kinetic Monte-Carlo (LKMC) simulations. The density functional theory is used to find the binding energies and jump barriers for P-V pair at different separations (from one to three interatomic bonds between complex constituents) and in different charge states. The mobility of the complex is simulated by LKMC with event probabilities calculated based on the energies from ab-initio calculations. .

Abstract: We present ultra-shallow diffusion profiles performed by short-time diffusion of boron from the gas phase using controlled surface injection of self-interstitials and vacancies into the ntype Si(100) wafers. The diffusion profiles of this kind are found to consist of both longitudinal and lateral silicon quantum wells of the p-type that are self-assembled between the layers of microdefects, which are produced by previous oxidation. These layers appear to be passivated during short-time diffusion of boron thereby forming neutral d - barriers. The fractal type selfassembly of microdefects is found to be created by varying the thickness of the oxide overlayer, which represents the system of microcavities embedded in the quantum well plane.