Influence of doping the base surface on parameters of a bipolar dual-collector lateral magnetotransistor

The effect of sensitivity inversion of magnetotransistors is studied using an instrument-technological simulation. The comparison of simulation results and experimental data enabled us to determine relations between sensitivity signs and distributions of injected charge carrier flows in structures of bipolar dual-collector lateral n-p-n magnetotransistors, the base of which is a diffused well (3CBMTBW). It is determined that the 3CBMTBW magnetotransistor with a small surface recombination velocity at the silicon-silicon dioxide boundary and with extraction of injected electrons by a base-well (substrate) p-n junction that is distant from the surface enables us to obtain a high sensitivity of 11 V/T at a good reproducibility and stability of parameters.     

Interpolyelectrolyte complexes of maleic acid copolymers and chitosan for stabilization and functionalization of magnetite nano‐ and microparticles

A facile method of preparation of stabilized and functionalized nano‐ and microparticles of magnetite by successive application of oppositely charged polymers with a regular structure of macromolecular chains (chitosan and maleic acid copolymers) onto Fe₃O₄ core are developed. This approach makes it possible to create two types of magnetite interpolyelectrolyte shells, containing carboxylic or amino groups in outer layer of shell. Composition and magnetic properties of composite particles depend on nature of the copolymer of maleic acid, reaction conditions and size of obtained particles. The carboxylic groups of copolymer in outer layer of interpolyelectrolyte shell were converted into reactive anhydride groups by heating. Thermal treatment also leads to covalent crosslinking of shell and improves stability of composites both in acidic and alkaline media. Horseradish peroxidase was successfully immobilized onto covalently crosslinked and activated microparticles of Fe₃O₄ in aqueous medium without of condensing agents. The proposed reproducible and low‐cost technique does not use toxic reagents or solvents at all stages, including preparation of Fe₃O₄, formation, activation and crosslinking, of magnetite shell, modification of activated surface of composite particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39663.     

Synthesis and Investigation of Solid Solutions Based on Indium Oxide in In<Subscript>2</Subscript>O<Subscript>3</Subscript>–MeO<Subscript>2</Subscript> (Me = Zr,Sn, Ti) Systems

Solid solutions in In₂O₃–MeO₂ (Me = Zr, Sn, Ti) systems based on indium oxide are synthesized by the coprecipitation method. It is found that the ultrasound treatment of the coprecipitation products reduces the degree of agglomeration of the initial particles by a factor of 3 and initiates the crystallization process of the precipitates. Nanocrystal (5–8 nm) precursor powders are obtained at 400°C. The optimal regime for sintering powders based on In₂O₃ to form a ceramic with a dense microstructure is chosen. The influence of the temperature, alloying additives, and the partial pressure of oxygen on the specific conductivity of indium oxide solid solutions is studied.     

An integrated magnetotransistor sensor

The initial voltage offset between the collectors in integrated circuits, including an npn-type dual-collector lateral bipolar magnetotransistor, formed in a well, and polysilicon resistors, is investigated experimentally. The choice of the switching circuit of the magnetotransistor determines the mode of operation and its effect on the offset. The initial offset between the voltages on the collectors is less than 1 mV, which enables the relative value of the useful signal in a weak magnetic field to be increased. Translated from Izmeritel’naya Tekhnika, No. 4, pp. 50–54, April, 2009.     

Study of the transport properties of organic semiconductors based on europium diphthalocyanine and bi-tris-phthalocyanine complexes with <Emphasis Type="Italic">ortho</Emphasis>-bis(oxymethyl)phenyl bridge and based on erbium and europium dinaphthalocyanine complexes

The transport properties of organic semiconductors based on europium diphthalocyanine and bitris-phthalocyanine complexes with ortho-bis(oxymethyl)phenyl bridge and based on europium and erbium dinaphthalocyanine are studied. The temperature dependences of the dc conductivity for all types of the structures under study are obtained; it is shown that all dependences include two activation portions. For high-temperature portions, the activation energies are determined as 0.85 eV for europium diphthalocyanine with the ortho-bis(oxymethyl)phenyl bridge, 1.135 eV for europium bi-tris-phthalocyanine with the orthobis(oxymethyl)phenyl bridge, 0.98 eV for europium dinaphthalocyanine, and 1.18 eV for erbium dinaphthalocyanine. For the low-temperature activation portion, it is shown that lanthanide ions and their bond with a ligand make the dominant contribution to the conductivity of the structures under study.