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R. Bourguiga - One of the best experts on this subject based on the ideXlab platform.

Aswini Ghosh - One of the best experts on this subject based on the ideXlab platform.

  • Hopping conduction in zinc vanadate semiconducting glasses
    Journal of Applied Physics, 2008
    Co-Authors: Aloka Ghosh, Debdutta Bhattacharya, Aswini Ghosh
    Abstract:

    In this paper, we have studied the electrical conductivity for different compositions of the zinc vanadate semiconducting glasses within a wide temperature range. We have analyzed the temperature dependence of the electrical conductivity within the framework of various Models for the Hopping conduction. We have observed that Mott’s phonon-assisted nearest neighbor Hopping Model of small polarons is appropriate for describing the conductivity data at high temperatures. We have further observed that at lower temperatures, Mott’s variable range Hopping Model is operative, while Greaves’ variable range Hopping Model is valid within the intermediate temperature range. The values of the density of states at the Fermi level, which are obtained from the analysis, are consistent with those for localized states.

  • Electrical properties of semiconducting barium vanadate glasses
    Journal of Applied Physics, 2000
    Co-Authors: Somaditya Sen, Aswini Ghosh
    Abstract:

    The preparation of vanadate glasses containing barium oxide and their electrical properties in the temperature range of 80–500 K have been reported in this article. Analysis of the electrical properties has been made in the light of different Hopping Models. The multiphonon assisted Hopping Model of small polarons in the nonadiabatic regime, proposed by D. Emin [Phys. Rev. Lett. 32, 303 (1974)] have been observed to describe the temperature dependence of the conductivity data of these glasses over the entire temperature range of measurement. The parameters obtained from the fits of the experimental data to this Model are reasonable and consistent with the glass composition. J. Schnakenberg’s Model [Phys. Status Solidi 28, 623 (1968)] is also consistent with the temperature dependence of the conductivity data. Mott’s optical phonon assisted Hopping Model at high temperatures provides smaller values of the localization length. However, Mott’s variable range Hopping Model is valid at low temperatures.

  • Semiconducting properties of magnesium vanadate glasses
    Journal of Applied Physics, 1999
    Co-Authors: Somaditya Sen, Aswini Ghosh
    Abstract:

    The electrical conductivity of semiconducting magnesium vanadate glasses has been reported for a wide composition range in the temperature range of 80–500 K. The experimental results have been analyzed in the framework of different Hopping Models. It has been observed that the multiphonon assisted Hopping Model of small polarons in the nonadiabatic regime, proposed by Emin, can interpret the temperature dependence of the conductivity data of these glasses over the entire temperature range of measurement. The parameters obtained from the fits of the experimental data to this Model appear reasonable and are consistent with the glass composition. On the other hand, Mott’s optical phonon assisted Hopping Model at high temperatures provides smaller values of the localization length. However, Mott’s variable range Hopping Model is consistent with the low temperature data. Schnakenberg’s Model yields higher values of the Hopping and the disorder energies than the activation energy obtained at the highest and the lowest temperature ranges.

  • Transport mechanism in nonconventional bismuth cuprate glass
    The Journal of Chemical Physics, 1996
    Co-Authors: Satyajit Hazra, Saptarshi Mandal, Aswini Ghosh
    Abstract:

    Temperature and compositional dependence of the electrical transport properties of the nonconventional binary bismuth cuprate glasses are reported for the first time. It has been observed that the phonon assisted small polaron Hopping Model in the nonadiabatic regime is consistent with the data only at high temperatures. The variable range Hopping Model can fit the low temperature data qualitatively. The polaron Hopping Models proposed by Schnakenberg [Phys. Status Solidi 28, 623 (1968)] and Emin [Phys. Rev. Lett. 32, 303 (1974)] can predict quantitatively the conductivity data in the entire temperature range of measurement for all glass compositions. The physical parameters obtained from the best fits of these Models are found reasonable and consistent with the glass compositions.

  • Electrical conduction in lead - iron glasses
    Journal of Physics: Condensed Matter, 1996
    Co-Authors: Saptarshi Mandal, Aswini Ghosh
    Abstract:

    Temperature and compositional dependences of electrical conductivity in lead - iron glasses are reported. The experimental results are analysed in the light of existing theories. It has been observed that the electrical conduction in these glass compositions at high temperatures is best described by Mott's phonon-assisted Hopping Model, while the low-temperature data are consistent with the variable-range Hopping Model. Hopping at high temperatures occurs in the non-adiabatic regime. The generalized Hopping Model of Schnakenberg is the best to interpret the temperature dependences of the conductivity and activation energy over the glass compositions studied. Values of the physical parameters obtained by the best fits of the experimental data are consistent with the glass compositions.

Régis Rogel - One of the best experts on this subject based on the ideXlab platform.

Ifor D W Samuel - One of the best experts on this subject based on the ideXlab platform.

  • discrete Hopping Model of exciton transport in disordered media
    Physical Review B, 2005
    Co-Authors: V M Burlakov, K Kawata, Hazel E Assender, G A D Briggs, Arvydas Ruseckas, Ifor D W Samuel
    Abstract:

    A Model of dispersive exciton transport has been developed for a medium with exciton energy levels randomly distributed in both space and energy scale. For a boxcar density of states of excitons an analytical solution is given describing the exciton density as a function of time and the proximity to the exciton quenching interfaces. The Model parameters, such as exciton lifetime, effective number of exciton energy levels within inhomogeneously broadened density of states, and Hopping distance and Hopping rate constants, could be determined using time-resolved photoluminescence data. The developed Model is verified via comparison with experimental data on the time-dependent photoluminescence decay of the conjugated polymer MEH-PPV and on the spectrum of internal quantum efficiency of the heterojunction photovoltaic device based on the MEH-PPV/TiO2 nanostructure.

S. Strässler - One of the best experts on this subject based on the ideXlab platform.

  • gauge factor of thick film resistors outcomes of the variable range Hopping Model
    Journal of Applied Physics, 2000
    Co-Authors: Claudio Grimaldi, Peter Ryser, S. Strässler
    Abstract:

    Despite a large amount of data and numerous theoretical proposals, the microscopic mechanism of transport in thick-film resistors remains unclear. However, recent low-temperature measurements point toward a possible variable-range-Hopping mechanism of transport. Here, we examine how such a mechanism affects the gauge factor of thick-film resistors. We find that at sufficiently low temperatures T, for which the resistivity follows the Mott’s law R(T)∼exp(T0/T)1/4, the gauge factor (GF) is proportional to (T0/T)1/4. Moreover, the inclusion of Coulomb gap effects leads to GF∼(T0′/T)1/2 at lower temperatures. In addition, we study a simple Model which generalizes the variable-range-Hopping mechanism by taking into account the finite mean intergrain spacing. Our results suggest a possible experimental verification of the validity of the variable-range Hopping in thick-film resistors.