372595871

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ANALYSIS, TESTING

JPRS-UMS-92-003 16 March 1992

induction and the dependence of the effective germa-nium distribution coefficient on the magnetic field strength are plotted. An analysis demonstrates that an increase in the magnetic field to 0.17 T increases the effective distribution coefficient of residual impurities by morę than twofold; moreover, the effective distribution coefficient increases with the magnetic field induction for both germanium and tellurium. Figures 2; refer-ences 4: 3 Russian; 1 Western.

Effect of Transverse Magnetic Field on Residual Impurity Concentration in InSb

927D0068M Moscow IZVESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2651-2652

[Article by A.N. Popkov, V.S. Vekshina, O.V. Nagibin, N.I. Pepiic, State Scientific Research and Design Insti-tute of Rare Earth Metals Industry]

U DC 66.046.522

[Abstract] The use of the methods of magnetohydrody-namic treatment (MGD) of semiconductor melts in order to improve the ąuality of the resulting BCC crystals is discussed; in particular, the effect of trans-verse magnetic field on the concentration of residual impurities in indium antimonide is examined. To this end, nondoped crystals were grown by Czochralski’s method in a quartz crucible with an MHD device for applying a transverse magnetic field. During the growing, the magnetic field was varied within 0-0.17 T. The resulting crystals had a diameter of close to 30 mm. The ciystals were then sliced into wafers for studying the electric and physical parameters at a liquid nitrogen temperaturę; an analysis shows that the total concentration of ionized centers is within (1.5-2) x 10¹⁴ cm'³, i.e., lower than that in crystals grown without the magnetic field by almost twofold. The use of magnetic field decreases the concentration of both n- and /Mype centers while the concentration of the former decreases to a greater extent than that of the latter. The dependence of the charge carrier mobility on the charge carrier concentration in InSb with and without the magnetic field is plotted graphically. The charge carrier mobility values of crystals grown in a magnetic field fali within lower concentrations. Figures 1; tables 1; references 5: 1 Russian; 4 Western.

Growing of Ge-Doped InSb Crystals Under Effect of Transverse Magnetic Field on Melt

927D0068L Moscow IZYESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2648-2650

[Article by A.N. Popkov, A.Ya. Polyakov, V.S. Vek-shina, O.V. Nagibin, State Scientific Research and Design Institute of Rare Earth Metals Industry]

U DC 548.55

[Abstract] Since semiconductor materials are character-ized by metallic conduction in a molten State, making it possible to use magnetohydrodynamic (MGD) treatment for controlling the hydrodynamic heat and mass transfer processes and thus determining the distribution unifor-mity of background impurities and dopants as well as the perfection of the resulting crystals, indium antimonide single crystals grown by Czochralski’s method under the effect of a transverse magnetic field on the melt are investigated. Indium antimonide was doped in a vacuum and crystals were grown at a magnetic flux density of 0-0.17 T; the initial charge carrier concentration in indium antimonide was 1 x 10¹⁴ cm'³ while the growth ratę was 0.5 mm/min. The charge carrier distribution and charge carrier mobility distribution in a germanium-doped InSb crystal grown in a 0.17 T magnetic field and the dependence of the charge carrier mobility on the charge carrier concentration in InSb<Ge> with and without the transverse magnetic field application are plotted and the recombination characteristics of p-type InSb samples grown with and without magnetic field are summarized. An analysis demonstrates that in growing Ge-doped InSb crystals, the carrier concentration starts dropping with an application of a transverse magnetic field to the melt while the charge carrier mobility increases; the latter is attributed to a decrease in the concentration of deep centers with an energy of £^+0.1 eV. Figures 2; tables 1; references 5: 3 Russian; 2 Western.

On Interrelation of Electric Conductivity and Porosity of Quasi-Isotropic Carbon Materials

927D0068I Moscow IZYESTIYA AKADEMII NAUK SSSR: SERIYA NEORGANICHESKIYE MATERIAŁY in Russian Vol 27 No 12, Dec 91 pp 2546-2551

[Article by I.Ya. Levintovich, A.S. Kotosonov, G.M. Butyrin, State Scientific Research Institute of Graphite-Based Structural Materials]

UDC 661.66.3+537.311.3

[Abstract] The interrelation of electric conductivity and porosity of quasi-isotropic carbon materials (UM) obtained by the ceramics technology is investigated; to this end, the relationship between the electric resistivity a and porosity, and especially the coefficient of connec-tivity—the ratio of the electric resistivity a to the resis-tivity along the crystal grain layer a,—are examined. The dependence of various porous structure parameters of the samples on their sintering temperaturę, the dependence of the samples’ electric resistivity on their micro-and macroporosity, and the dependence of specific resis-tivity of the samples on their total porosity with a change in temperaturę are plotted. An analysis of experimcntal data shows that the volume shrinking of coke-based materials during their heat treatment is uniform and the relative volume of macropores remains unchanged. A change in microporosity due to microstructural defects