Search Results

1 - 10 of 12 items

  • Author: V. Gerbreder x
Clear All Modify Search

Abstract

CuInSe2 (CISe) compound was produced by high-temperature synthesis. After mechanical milling, the average CISe particle size decreased to 10μm. The authors study structural changes of the compound after ablation in liquid by a 1064 nm pulsed laser. The SEM examination indicated the presence of spherical particles with the average size of ~ 450 nm. A nonlinear relationship was established between the laser radiation dose and the quantity of spherical particles. The XRD analysis has shown an improvement in the CISe crystalline structure and the absence of significant changes in its stoichiometry. The 3 μm thick experimental CISe samples were screen-printed on planar Ni electrodes, and improvement also was revealed in their photosensitivity. The conclusion is that the pulsed-laser ablation can be applied to chalcopyrite structures like CISe without destruction of their initial properties.

Abstract

Well-structured ZnO nanotubes are obtained by a self-selective etching method with lowering temperatures of growth during the hydrothermal process.

The structural and optical properties of the obtained nanostructures are investigated by various conventional methods.

The goal of the research is to compare the efficiency of ZnO nanotubes to that of ZnO nanorods during lead adsorption process from aqueous solution and demonstrate that hollow nanostructures are more effective than solid nanostructures of the same morphology due to their larger effective surface.

Both nanotubes and nanorods are obtained under similar growth conditions: neither growth solution composition, nor concentration is changed. ZnO morphology is switched only by changing temperature during the growth process.

The measurements are carried out to assess the efficiency of the adsorption per unit weight of ZnO nanorod and nanotube capacity of static adsorption.

Principles of Creation and Reconstruction of Dot-Matrix Holograms

A method for calculation of dot-matrix holograms is presented, whose distinction from other methods is simplicity of the formulas for the parameters of each pixel element in a hologram. At the Innovation Spectroscopy Center of DU a device for recording dot-matrix holograms has been designed, with a program using the pro-posed method for their calculation. Holograms 50x50 mm in size well corresponding to the initial graphic design were obtained.

Surface Modification of SB-SE Thin Films by Laser Irradiation and Etching

The surfaces of Sb20Se80 and Sb40Se60 thin films were modified by exposure to laser light. To study the topology of these surfaces the scanning force microscopy was used. As a result, the surface of as-deposited/amorphous SbxSe100-x films appear to be flat, while the treated films exhibit three types of surface structure on the sub-micrometer scale. Changes in the surface characteristics as well as potential applications of selective etching of Sb-Se thin films are discussed.

Abstract

Optimal growing parameters have been found using the hydrothermal method to obtain well-aligned vertical ZnO nanorod and nanotube arrays. The influence of different growing factors (such as temperature, growing solution concentration, method of obtaining seed layer and condition) on nanotube morphology and size is described in the paper.

Well-structured ZnO nanotubes have been obtained by using a selfselective etching method with lowering temperatures of growth during the hydrothermal process.

It is shown that the optical properties of the nanostructure arrays obtained are sensitive to the medium in which they are placed, which is why they can be used as sensors for pure substance detection and in different solutions for impurity determination.

Abstract

The present paper presents the method for obtaining core/shell CuO-ZnO nanoparticles and nanocoatings by using a commercially available vacuum coating system. Initially generated Cu-Zn core/shell nanoparticles have been oxidised with a highly reactive atomic oxygen beam. Second-harmonic generation has been observed in the obtained samples. The dependence of second- harmonic intensity on the wavelength of the exciting radiation is shown in the paper.

Abstract

The structuring features of As38S18Se44 chalcogenide (ChG) inorganic glasses were studied using electron beam (EB) lithography. After the EB exposure, ChG thin films are etched in a high-selectivity alkaline amine, with the dissolution rate being linearly proportional to the electron dose. The Gaussian EB intensity profile is well replicated in the shape of individual lines, which allows high-resolution smoothlyshaped nanostructures to be obtained. The height of developed patterns can be controlled through changing the applied electron dose. These features make the proposed technique widely applicable in the fields of photonics and optics. The results obtained would help to better understand the processes occurring in ChG thin films at recording the diffractive gratings, and thus achieve a better profile and surface roughness control.

Abstract

The simple analysis method has been introduced for the kinetic analysis of the hydrothermal growth. The zinc oxide nanorod arrays have been synthesized via a hydrothermal process. Zinc nitrate hexahydrate (Zn(NO3)2 · 6H2O) has been used as the precursor in the presence of hexamethylenetetramine (C6H12N4) for the formation of ZnO nanostructures. Long-term isothermal growth kinetics of ZnO nanorods has been investigated. The effect of the solution temperature (70-90 ℃) on the kinetics of the hydrothermal growth of ZnO nanorods has been examined. An extensive analysis by scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction has revealed that the as-synthesized ZnO nanorod arrays are well-crystalline and possessing hexagonal wurtzite structure. These ZnO films have promising potential advantages in microelectronic and optoelectronic applications.

Selective Wet-Etching of Amorphous/Crystallized Sb-Se Thin Films

The paper is focused on the development of an in situ real-time method for studying the process of wet chemical etching of thin films. The results of studies demonstrate the adequate etching selectivity for all thin film SbxSe100-x (x = 0, 20, 40, 50, 100) compositions under consideration. Different etching rates for the as-deposited and laser exposed areas were found to depend on the sample composition. The highest achieved etching rate was 1.8 nm/s for Sb40Se60 samples.

ELECTRIC CONDUCTIVITY OF Sb/Se THIN FILM MICRO-SCALE STRUCTURES

Research into the phase change transition (PCT) from amorphous to crystalline state in chalcogenide glass semiconductors is often more associated with large-scale samples. The authors present a micro-scale structural model of the Sb/Se thin films. They have also extended the investigations of photo- and thermo-stimulated inter-diffusion and PCT effects between two adjacent layers. The results show that the optical and electrical characteristics of such a film change simultaneously. It has been found that the electric conductivity of the films increases 3 times during a PCT process.