Дана концепция и теоретическая основа метода трехкомпонентной зонной плавки для выращивания монокристаллов полупроводниковых твердых растворов с использованием затравок из составных компонентов. В пфанновском приближении решена задача аксиального концентрационного распределения компонентов в монокристаллах Ge-Si, выращенных при различных значениях операционных параметров, таких как длина расплавленной зоны и состав исходных макрооднородных стержней твердых растворов. Анализ полученных результатов определяет потенциал метода и оптимальные условия для выращивания монокристаллов с заданными однородным и градиентным составами во всем непрерывном ряду твердых растворов Ge-Si. Показана перспективность метода трехкомпонентной зонной плавки для выращивания монокристаллов полупроводниковых твердых растворов. Ключевые слова: Полупроводниковые твердые растворы, распределение компонентов, материал затравки.

Рассмотрено явление переноса положительных ионов металла с поверхности массивного анода на поверхность цеолитовой пластины в аномально малом для этого явления внешнем электрическом поле. Объяснение наблюдаемого явления основано на том, что в электрическом поле на проводящих порах цеолита вблизи анода возникает отрицательный заряд, локализованный на стенках пор, создающий аномально большое локальное электрическое поле на поверхности анода. Это поле осуществляет перенос ионов с анода на поверхность цеолита. Приведены соображения, объясняющие пороговый (по величине внешнего поля) характер явления. Ключевые слова: цеолит, ионный обмен, ионы серебра, массоперенос.

The transfer of positive metal ions from the surface of a massive anode on a zeolite plate in an electric field that is anomalously low for this process has been considered. An explanation given to this phenomenon relies on the fact that an electric field produces a negative charge in the conductive pores of zeolite near the anode. This charge localizes on the walls of pores and generates an anomalously high local electric field on the surface of the anode. This field provides ion transfer from the anode to the zeolite surface. The presence of a threshold external field for this phenomenon has been explained.

AbstractConductivity inversion in thin n -InSe films under intense pulsed laser irradiation was obser. A p – n structure based on indium selenide formed between irradiated and nonirradiated regions of a thin-film sample. It was confirmed by EDAX analysis that the composition of the sample remained the same after irradiation. The conductivity inversion is attributed to a change in the dynamics of lattice defects under heating.

Conductivity inversion in thin n -InSe films under intense pulsed laser irradiation was obser. A p – n structure based on indium selenide formed between irradiated and nonirradiated regions of a thin-film sample. It was confirmed by EDAX analysis that the composition of the sample remained the same after irradiation. The conductivity inversion is attributed to a change in the dynamics of lattice defects under heating.

The effect of submicron ferroelectric BaTiO3 particles on the dielectric and electro-optical properties of the smectic-A liquid crystal (LC) with a high negative dielectric anisotropy is investigated. It is shown that the addition of BaTiO3 particles with a weight amount of 1% reduces insignificantly the transverse dielectric permittivity component ε⊥ of, but significantly increases the longitudinal dielectric permittivity component ε// of the smectic-A LC. As a result, the anisotropy of the dielectric permittivity Δε = ε// − ε⊥ of the smectic-A LC decreases. The addition of BaTiO3 particles shifts the dispersion ε⊥ toward lower frequencies. Both components of the electrical conductivity of LC colloid + BaTiO3 are an order of magnitude higher than of the pure LC. The threshold voltage of the homeotropic-planar transition of the colloid is twice smaller, and its velocity is 6 times higher in comparison with the pure LC. A simple model explaining qualitatively all results obtained is presented.

This study explores, for the first time to our knowledge, the influence of electret state on the dielectric parameters of porous zeolite of frequencies up to 106 Hz, at room temperature and normal atmospheric pressure. The I-V characteristics with unusual hysteresis loop in the wide pressure range were measured on zeolite plates having three different material characteristics: A) plate, cut out from a monoblock natural zeolite; B) plate, modified by silver ions, and C) plate containing silver nanoparticles. Zeolite samples were exposed to an electric field (E-p = 2 kV cm(-1)) in an air atmosphere for 240 min. It is established, that the stability of electret state and value of the dielectric response epsilon' and epsilon" for clinoptilolite Ag nanoparticles containing plates changed under influence of DC electric field. During some time the dielectric response is restored and observed unique phenomenon indicates on the electret behavior of clinoptilolite samples. These changes are observed within a few days consequently, there is long-term dynamics of the dielectric response changes. This interpretation is based on the assumption that due influence of the dc electric field part of the silver atoms in nanoparticles decays into ions and electrons. (C) 2017 Elsevier Ltd. All rights reserved.

A one-dimensional problem of the axial distribution of Al and In impurities in uniform crystals of Ge–Si solid solutions grown by double feeding of the melt method has been solved in the Pfann approximation. The mathematical modeling results suggest that the impurity concentration profile in Ge–Si crystals of constant composition can be varied in a wide range through appropriate changes in the relationship between the crystal growth rate and the rates of feeding the melt using germanium and silicon rods. We demonstrate the possibility of growing completely homogeneous Ge–Si kAl,Inl crystals, in terms of both the concentrations of their major components and the impurity concentration profile.

The aim of this study was to characterize electrical conductivity and dielectrical properties of the silver-exchanged zeolite-natural clinoptilolite from Western part of Turkey and Azerbaijan in the range of frequencies from 200 Hz to 1 MHz and at room temperature. For a better understanding the effect of concentration and content of silver in the nanoporous zeolite volume on the conductivity, a study of the dielectric properties of an un-modified and silver-modified zeolite plates with different amounts of Ag ions and Ag nanoparticles is performed. Un-modified and three different types of the silver ion-exchanged modified clinoptilolite plates were prepared. It was found, that with increasing silver concentration, resistance of zeolite plate monotonically decreases at the same time a capacitance is increases. It is suggested an explanation of the observed frequency dependence of the capacitance and resistance of zeolite plates on the silver concentrations may be explain on the basis of an electrode-dielectric interface gap model. At the same time, the observed phenomenon can be explained by considering the fact that with increasing content of silver the conductivity increases. These results show that Ag nanoparticles play significant role for performance improvement in plasma electronic devices with zeolite cathode. (C) 2016 Elsevier Ltd. All rights reserved.

Based on experimental data on the temperature dependences of the free carrier concentration in complex-doped Ge1 − x Si x 〈Ga,Ni〉 crystals (0 ≤ x ≤ 0.25), it is established that sample quenching at 1020–1050 K leads to the formation of additional acceptor centers in them. The activation energy of these centers increases with an increase in silicon content in the matrix and is described by ratio E k x = E v + (75 + 420x) meV. Crystal annealing at 550–570 K leads to the disappearance of additional acceptor levels. An analysis of the data shows that the most likely model for these deep acceptors is a complex composed of substituent nickel and gallium atoms (Ni s Ga s ) or an interstitial nickel atom and a substituent gallium atom (Ni i Ga s ). It is established that the generation of additional electroactive centers in Ge1 − x Si x 〈Ga,Ni〉 must be taken into account in precisely controlling the electronic properties of crystal via the decomposition of supersaturated solution of nickel impurity in the matrix.

A concept and fundamentals of a hybrid technique for growing homogeneous single crystals of semiconductor solid solutions (SSs) from melt are presented. The growth consists of two stages. In the first stage, a single crystal with a specified concentration of the more refractory component is grown by an innovative method of directional constitutional supercooling of a melt in the steady-state mode. In the second stage, the melt is fed with the second component. Using an example of the classical Ge-Si system, the concentration profiles of the components along the crystal axis are calculated and the SS growth dynamics ensuring single crystallinity over the entire ingot length is determined. An analysis of the results yields the optimal technological parameters and conditions for growing homogeneous single crystals of SSs of a specified composition and size.

The emission from impurity states of silver (an element of the IB subgroup) in a Ge-Si alloy, containing 18 at % Si, has been studied. The donor level of silver has been found in crystals doubly doped with gallium and silver, while its first acceptor level has been revealed in crystals doped with only silver. Single crystals were grown by pulling from a melt using a feeding rod. Doping with gallium was performed by introducing this element into the feeding rod, and silver was introduced into the crystals via diffusion. The positions of the donor and first acceptor Ag levels with respect to the top of the valence band were found by analyzing the temperature dependence of the Hall coefficient and the electroneutrality equation for the crystal: 0.06 and 0.29 eV, respectively.

The possibility of obtaining single crystals of binary solid solutions exhibiting strong segregation upon crystallization by pulling from a feeding melt with the use of a crucible shaped as a truncated cone and a feeding ingot of complex shape is shown. The composition distribution along the crystal length is found by solving the continuity equation for the second component flux under certain initial and boundary conditions. It is shown that single crystals can be obtained in which the second-component concentration in the stationary mode exceeds the corresponding value in the feeding ingot. The method developed is applied to Ge-Si solid solutions.