Mo/Ni and Ni/Ta–W–N/Ni thin-film contact layers for (Bi,Sb)<Subscript>2</Subscript>Te<Subscript>3</Subscript>-based intermediate-temperature thermoelectric elements

We have examined the possibility of utilizing thin-film contact layers for producing reliable Ohmic contacts to proposed intermediate-temperature (Bi,Sb)₂Te₃-based thermoelectric materials with improved thermoelectric properties, which allow the working temperature range to be extended to 600 K. Three contact configurations have been produced by ion-plasma magnetron sputtering: a single Ni layer, Mo/Ni bilayer, and Ni/Ta–W–N/Ni three-layer system. It has been shown that reliable contacts can be produced using Mo/Ni and Ni/Ta–W–N/Ni layers, which prevent interdiffusion between the materials to be joined and ensure good adhesion to the thermoelectric element.     

The effect of axisymmetric two-dimensional magnetic field on the configuration of vacuum-arc plasma

An experimental investigation is made of the effect of axisymmetric two-dimensional magnetic field on the forming of plasma and on the configuration of cathode spots in a vacuum-arc discharge. It is demonstrated that a magnetic field with a transverse (relative to the discharge axis) component has a significant effect on the shape of plasma column and on the rate of expansion of the cathode spot region. In a magnetic field, arc plasma has the form of truncated cone expanding toward the anode. The cathode spots take up a part of the cathode area which decreases with increasing magnetic field. Arguments are given in support of the assumption that the arrangement of cathode spots and the form of arc plasma are defined by the minimum principle similar to the Steinbeck principle. In so doing, the displacement of spots is caused by their emergence in a new region corresponding to a lower arc voltage. Also discussed is the mechanism associated with retrograde motion of cathode spot in view of the effect of azimuthal magnetic field on the axial component of current and of the effect of axial magnetic field on the azimuthal component of current.     

Phase relations in the HgCr2Se4-CdCl2 system

The phase relations in the HgCr₂Se₄-CdCl₂ system have been investigated using differential thermal analysis and x-ray diffraction, and the primary crystallization field of the spinel phase in this system has been located: 560–750°C, 84–97 mol % CdCl₂. By optimizing growth conditions and using CdCl₂ as a flux, single crystals of Hg_1?x Cd_xCr₂Se₄ solid solutions containing up to 5 wt % Cd have been grown.     

Physicochemical principles behind the preparation of high-purity arsenic compounds from lewisite detoxification products

High-purity arsine suitable for the growth of gallium arsenide-based epitaxial heterostructures has been prepared by processing a lewisite detoxification product: hydrolytic sodium arsenite. The proposed method involves the dissolution of hydrolytic sodium arsenite in water; electrolysis of the solution, resulting in the formation of arsenic acid and sodium hydroxide, which is subsequently used to absorb released chlorine; electrochemical arsine synthesis from the arsenic acid; and arsine purification by fractionation to a level of 99.9999%.     

A general simulation procedure for the electrical characteristics of metal-insulator-semiconductor tunnel structures

The algorithm is suggested for calculating the I–V characteristics of a voltage- or current-controlled metal-tunnel-thin insulator-semiconductor system. The basic underlying physical models are discussed. Applicability of the algorithm is confirmed by a comparison of the simulation results with the measurement data obtained by the authors and borrowed from the literature, for several different structures. The presented information is supposed to suffice for calculating the electrical characteristics of the investigated structures with the various combinations of materials: metal or polysilicon gate, single-layer or stacked insulator, and semiconductor with any doping type and level.