Diagnostics of high-resistivity GaAs wafers by microwave photoconductivity

It is demonstrated that the method of microwave photoconductivity developed previously for the study of ultrapure Si can be successfully employed in the qualitative diagnostics of pure high-resistivity GaAs. Data on the microwave photoconductivity of GaAs are in good agreement with the results of measurements of the Hall effect, C-V characteristics, and low-temperature photoluminescence.     

Photoelectric C-V profiling of majority charge carriers and effective lifetimes of minority charge carriers in gettered GaAs wafers

The procedure for photoelectrochemical C-V profiling of the concentration of majority charge carriers and effective lifetimes of minority charge carriers in high-resistivity thick (1.6 mm) GaAs wafers subsequently to their gettering is described. Gettering was performed by both one-side and two-side coating of the wafers with a Y film and subsequent thermal treatment at 700 and 800°C. It was demonstrated that the concentration profile N _d-N _a and the effective lifetime for minority charge carriers throughout the wafer are rather uniform in both cases. This procedure makes it possible to measure the charge carrier concentration as low as 10¹² cm^?3.     

Erythrocyte induced structurization of a liquid crystal mesophase

The phenomenon of structurization of a nematic liquid crystal (NLC) mesophase under the action of introduced non-electrically-neutral biological components is demonstrated for the first time in a system with the charged component represented by human blood erythrocytes. The observed effect is considered as being quite general and not contradicting to the results obtained previously for the structurization of NLCs under the action of fullerene-containing complexes with charge transfer.     

Improvement of the equipment in fast-neutron reactor facilities

Information is presented on the development of the main equipment of the BN-1200 advanced reactor facility: first- and second-loop main circulation pumps, intermediate heat exchanger, actuation mechanism of the cold filter-trap control and protection system, autonomous and air heat exchangers, steam generator. The approach to the development of the equipment is based on maximum use of the experience gained in operating BN-350 and -600 as well as experience in developing the BN-800 design, which gives a basis for ensuring reliable operation of the BN-1200 equipment. New solutions for improving the technical-economic indicators and increasing the safety of a power-generating unit, whose validation required R&D work, are examined at the same time.     

The Optical Effect of Light Polarization Plane Rotation in DNA-Containing Materials

Technical Physics Letters - Using the example of DNA water solutions, a manifestation of the light polarization plane rotation effect has been shown (in comparison with a number of dyes). Numerical...     

Depth profiles of the majority carrier concentration and the minority carrier effective lifetime in gettered GaAs

The first results are reported on the concentration profiles of majority carriers and the effective lifetime profiles of minority carriers in thick (1.6 mm) GaAs plates subjected to surface gettering. It was established that the one-and two-sided coating of the GaAs plates with Y films, followed by heat treatment at 700–800°C, allows a high-resistivity material to be obtained with homogeneous distributions of the electron concentration and the hole lifetime in depth of the semiconductor.     

Measuring the nuclear charge of fission fragments using a large ionization chamber—part of the double-arm time-of-flight spectrometer

Identification of decay products is a relevant task in studying rare collinear decays of low excited heavy nuclei. A technique for measuring the nuclear charge of decay products detected by a wide-aperture ionization chamber—a part of the double-arm time-of-flight spectrometer—is described. Two versions of nuclear charge calibration using data of the reaction ²³⁵U(n _th, f) have been developed to determine the charge of the decay products. Testing with simulation data shows that the use of charge parameterization based on the Bohr-Willer empirical equation in the calibration procedure makes it possible to determine the nuclear charge of the fission fragments over a wide energy range. The charges of light ions from He to C, predicted on the basis of this approach, appear to be overestimated by two charge units.