Papers by Keyword: Surface Pattern

Abstract: It has been shown that the plane surface of a stressed solid can become morphologically unstable relative to the perturbations of the electron density. The above instability is referred to as dynamic and evolves under the relaxation mechanism determined by the electron-electron interaction. The development of the dynamic instability is accompanied by the formation of a dynamic pattern differing from that which is formed under elastic-diffusion instability. To describe the dynamic pattern, a method has been proposed which takes into account the dynamic displacements of the atoms caused by a change in the interatomic interaction during the electron density redistribution. The origin of the different types of the pattern earlier observed experimentally on the free surface of the stressed solids has been explained. The dynamic displacements of the atoms have been shown to stimulate the diffusion mass transfer resulting in a change of the value and the sign of the diffusion coefficient.

Abstract: This paper deals with optical and electrical simulations of 4H-SiC UV-Photodetectors based on pn junctions. The simulations are performed under the UV light, with wavelengths varying between 200 nm and 300 nm. Under reverse bias, the simulation results point out the influence of surface patterns on the current density. The studied structures of the patterns consist in a semicircle with or without a flat surface. The patterned surfaces are parametrized according to the semicircle radius R and the flat surface length L. We show that the optical absorption strongly depends on these parameters, giving a maximum value whatever the wavelength with R = 100 nm and L = 0 nm (no flat surface). However, to optimise the carrier harvest, it is important for the space charge region to be situated in a zone where the optical generation is high. This study shows that the photodetector current density increases within three orders of magnitude (from 9x10^-14 A.cm^-2 to 3x10^-10 A.cm^-2), by using the specific surface pattern given above.

Abstract: Effect of rare earth content on microstructure and interfacial reactions of low Ag content SnAgCu solder is researched by adopting the X-ray diffraction, JSM-5610LV scanning electronic microscope, energy spectrum analysis and JEM2100 ultrahigh resolution electron microscopy. The results show that proper quantities of rare earth (0.1%) can refine the eutectic microstructure of the solder alloy; and petal-like rare earth compound can be found in the solder alloy while the rare earth addition is 0.5%. The growing rate of the interfacial intermetallic compound can be reduced during the soldering with adding 0.1% rare earth in the Sn2.5Ag0.7Cu solder alloy.

Abstract: Surface analysis of the aluminum thin plates plastically deformed under constrained cyclic deformation was performed by Fourier, morphology and fractal techniques. The plates are used for estimation of deformation damage and fracture in places with a priori known homogeneous and heterogeneous strain distribution. Advantages and disadvantages of Fourier, morphology and fractal techniques for characterization of the intersections and projections are discussed in the context of its applicability to investigation of plastic deformation and fracture (persistent strain planes and directions, strain localization angles and places, etc.).

Abstract: Gold nanowires, 50 nm in diameter and 1-2 μm in length, were prepared by template synthesis and modified by bifunctional thiols then suspended in different solvents. The dispersibility of nanowires is found to be strongly affected by the selection of solvents. The functionalized gold nanowires can be selectively assembled onto patterned surface via electrostatic interactions. It is possible that this simple process can be carried out in fabrication of more complicated structures, which are potentially useful in many applications such as nanoelectronic, photonic and SERS.

Abstract: Molding characteristics are presented for the surface pattern of polymeric materials in injection molding. They are related to the polymer properties and surface roughness of the etched mold. The polymer structure and the mold roughness can affect roughness deviation and surface duplication quality on polymers. Experiments are performed with respect to the surface roughness analysis. It is expected that the duplication properties can contribute to molding process of surface pattern in injection molding.