Экологический аудит радиоактивного загрязнения территории: проблемы и возможные пути их практического решения

Ecological audit of radioactive territory pollution is a special field of ecologic-legal relationship. Development of special methodology is needed for its practical implementation. Authors analyze main problems and successive stages of that procedure.Экологический аудит радиоактивного загрязнения территории представляет собой особую область эколого-правовых отношений. Для внедрения его в практику требуется разработка специальной методологии. Авторами рассмотрены основные проблемы и последовательные этапы данной процедуры

Self-heating effects in AlGaN/GaN HEMT heterostructures: Electrical and optical characterization

The effect of self-heating on the transport characteristics and electronic properties of transistor AlGaN/GaN heterostructures was investigated. The electrical, micro-Raman and photoluminescence techniques were used for temperature estimations for transistor structures under electrical load. The thermal resistance of these structures has been calculated to obtain the temperature of conducting channel heating from the current-voltage characteristics. The differences in the obtained temperature data from applied techniques have been analyzed

Current instabilities in resonant tunnelling diodes based on GaN/AlN heterojunctions

Present paper studies double barrier resonant tunnelling diodes (DB-RTD) based on GaN/AlGaN heterostructures, grown by plasma-assisted molecular beam epitaxy (PA-MBE). Tunnel (current-voltage, I–V) and capacitance (capacitance-voltage, C–V) spectroscopy measurements were performed at the temperature range from 4.2 to 300 K. It has been found that measured characteristics of DB-RTD have complex nonlinear behavior and reveal the current discontinuities of I–V curves. The features can be explained by the existence of polarization fields and interface defects. These effects strongly influence on the potential profile of the DB-RTD heterostructures. To understand physics of the processes, numerical simulations of the given structures, using a model based on real-time Green’s functions, have been performed. Comparative analysis of experimental and numerical data showed that the current instability and nonlinearity of characteristics of the nitride based DB-RTD can be connected with trapping the electrons onto interfacial and dislocation states in these heterostructures

Investigation of resistance formation mechanisms for contacts to n-AlN and n-GaN with a high dislocation density

We studied temperature dependences of the resistivity, Pc(T) , of Pd-Ti-Pd-Au ohmic contacts to wide-gap semiconductors n - GaN and n - AlN with a high dislocation density. BothPc(T) curves have portions of exponential decrease, as well as those with very slight Pc(T) dependence at higher temperatures. Besides, the Au-Pd-TiPd-n-GaN contacts have a portion of Pc(T) flattening out in the low-temperature region. This portion appears only after rapid thermal annealing (RTA). In principle, its appearance may be caused by preliminary heavy doping of the near-contact region with a shallow donor impurity as well as doping in the course of contact formation owing to RTA, if the contact-forming layer involves a material atoms of which serve as shallow donors in III N compounds. The obtained Pc(T) dependences cannot be explained by the existing mechanisms of current transfer. We propose other mechanisms explaining the experimental Pc(T) curves for ohmic contacts to n - GaN and n -AlN

Quasielastic axial-vector mass from experiments on neutrino-nucleus scattering

We analyze available experimental data on the total and differential charged-current cross sections for quasielastic neutrino and antineutrino scattering off nucleons, measured with a variety of nuclear targets in the accelerator experiments at ANL, BNL, FNAL, CERN, and IHEP, dating from the end of sixties to the present day. The data are used to adjust the poorly known value of the axial-vector mass of the nucleon.Comment: 27 pages, 19 figures. Typos corrected; tables, figures and references added, discussion extended; matches published versio

Physics with charm particles produced in neutrino interactions. A historical recollection

Results obtained in neutrino unteractions on charm particles are presented

On the impact of the laser radiation wavelength and the concentration of quantum dots on the luminescence spectra of colloid solution and QD-doped nanocomposites

The influence of the concentration and the laser excitation wavelength on the width and luminescence spectrum maximum of CdSe/CdS /ZnS quantum dots in the toluene solution and doped on the glass plate was studied. It was shown that the wavelength of the exciting laser does not affect the width and peak center of the luminescence spectrum of the samples under the study. Possible mechanisms of the quantum dots concentration influence on studied parameters are analyzed

On the impact of the laser radiation wavelength and the concentration of quantum dots on the luminescence spectra of colloid solution and QD-doped nanocomposites

The influence of the concentration and the laser excitation wavelength on the width and luminescence spectrum maximum of CdSe/CdS /ZnS quantum dots in the toluene solution and doped on the glass plate was studied. It was shown that the wavelength of the exciting laser does not affect the width and peak center of the luminescence spectrum of the samples under the study. Possible mechanisms of the quantum dots concentration influence on studied parameters are analyzed