Results 1 - 10 of 409
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[en] Current–voltage (I–V) characteristics of conductance in multigrain layers of submicron particles of silicon, gallium arsenide, indium arsenide, and indium antimonide have been studied. Nanoparticles of all semiconductors were obtained by processing initial single crystals in a ball mill and applied after sedimentation onto substrates by means of electrodeposition. Detailed analysis of the I–V curves of electrodeposited layers shows that their behavior is determined by the mechanism of intergranular tunneling emission from near-surface electron states of submicron particles. Parameters of this emission process have been determined. The proposed multigrain semiconductor structures can be used in gas sensors, optical detectors, IR imagers, etc.
[en] The influence of low doses of γ rays on the capacitive properties of structures based on mesoporous silicon has been investigated. The concentration distribution of dangling charged bonds over the layer depth, which changes under irradiation, has been found using the capacitance–voltage characteristics at different frequencies of the test signal. It is shown that the concentration and relaxation time of surface charged states in a structure with a mesoporous silicon layer decrease under γ irradiation, which makes the material promising for devices with controlled reactance (varactors) that are resistant to γ irradiation.
[en] The results of the study of vitreous Se films obtained by a method of vacuum-thermal evaporation after their laser modification are presented. It is shown for the first time that a low-power laser irradiation of the film at a wavelength of 632.8 nm and room temperature results in a nucleation and growth of nanocrystallites of monoclinic and rhombohedral Se in an amorphous matrix of the film. The formation of the stable hexagonal Se phase is not observed. The appearance of nanocrystallites with an average size of ~20–30 nm is accompanied by a growth of a reflection coefficient of the film. The established new optical and structural properties of the formed films are stable in time at room temperature.
[en] The kinetics of coloration in thin hydrogenated vanadium pentoxide films under the internal electrochromic effect is studied alongside with the influence of their hydrogenation by means of plasma-immersion ion implantation on this process. The variant of uniform implantation and the nonuniform case when a film is partially subjected to ion treatment are considered. Based on the experiments on measuring the electrochromically colored surface area growth rate and the passing current, it has been revealed that the electrochromic effect becomes much stronger in the nonuniform variant, when the cathode is placed on the nonhydrogenated part of a film, and the anode is located on its hydrogenated part.
[en] Experimental data on the influence of neutron irradiation on the plasticity characteristics of chromium–nickel austenite steels have been analyzed. Special attention is devoted to detection of anomalously high plasticity levels attained at some parameters of irradiation and deformation, which is explained by the formation and propagation of a “phase transformation wave” in the metastable steel. Necessary and sufficient conditions for the realization of this wave are formulated.
[en] A design of a magnetic shutter for a trap made of permanent magnets for the ultracold neutron storage in experiments on measuring the neutron lifetime is proposed. The data of shutter testing and comparison with the calculated magnetic fields are reported.
[en] The results of the development and experimental investigation of the gated-viewing method without the using an image intensifier as a fast shutter are presented. The device for implementing the method consists of an interline CCD image sensor with an input lens and 906 nm pulsed laser diode with an output lens that forms an illumination beam. The gated-viewing method is based on the original CCD control procedure, which allows observing multiple pulses without lowering the frame rate. Experimental studies have shown the method feasibility under conditions of smoke and fog.
[en] Photovoltaic characteristics of more than 20 types of AlGaAs-based light-emitting diodes operating in the 830- to 970-nm wavelength range have been considered. It is established that AlxGa1– xAs semiconductor structures employed in these devices can also be used for manufacturing photovoltaic converters of monochromatic radiation with quite high efficiency.
[en] Results of experimental investigations of directly synthesizing nanocrystalline titanium diboride in a hypervelocity jet of electrodischarge plasma generated by a pulse high-current coaxial magnetoplasma accelerator with titanium electrodes are presented. The main result of the investigations is manufacturing a product with a mass of up to ∼3 g containing more than 90% of titanium diboride obtained mostly in the form of hexagonal and dodecagonal particles.
[en] A new approach to quantitative analysis of the concentration of boron atoms in diamond using secondary- ion mass spectrometers with time-of-flight mass analyzers is proposed. Along with the known boron-containing lines (B, BC, BC2), many lines related to cluster secondary ions BCN have been found in the mass spectrum; their intensity increases by one or two orders of magnitude when Bi3 probe ions are used. Lines BC4, BC6, BC2, and BC8 have the highest intensity (in the descending order); when they are summed, the sensitivity increases by an order of magnitude in comparison with the known mode of detecting BC2. The parameters of the boron δ-layer in single-crystal diamond films grown under optimal conditions have been measured to be unprecedented: the δ-layer width is about 2 nm, and the concentration is 6.4 × 1020 cm–3 (the boron concentrations for doped and undoped diamonds differ by four orders of magnitude).