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  1. No Access

    Article

    Structure and Phase Composition Study of Heavy Doped with Carbon Thin Films of TiO2 : C Deposited by RF Magnetron Sputtering

    The aim of the present research is to study some aspects of the carbon do** of TiO2 thin films and the influence of low temperature thermal annealing on the phase precipitation in thin films. Тhin films of heav...

    T. Milenov, P. Terziyska, G. Avdeev… in Russian Journal of Inorganic Chemistry (2022)

  2. Article

    Open Access

    Prospects for microwave plasma synthesized N-graphene in secondary electron emission mitigation applications

    The ability to change the secondary electron emission properties of nitrogen-doped graphene (N-graphene) has been demonstrated. To this end, a novel microwave plasma-enabled scalable route for continuous and c...

    N. Bundaleska, A. Dias, N. Bundaleski, E. Felizardo, J. Henriques… in Scientific Reports (2020)

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  3. Article

    Open Access

    Large-scale synthesis of free-standing N-doped graphene using microwave plasma

    Direct assembling of N-graphene, i.e. nitrogen doped graphene, in a controllable manner was achieved using microwave plasmas at atmospheric pressure conditions. The synthesis is accomplished via a single step ...

    N. Bundaleska, J. Henriques, M. Abrashev, A. M. Botelho do Rego… in Scientific Reports (2018)

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  4. Article

    Open Access

    Towards large-scale in free-standing graphene and N-graphene sheets

    One of the greatest challenges in the commercialization of graphene and derivatives is production of high quality material in bulk quantities at low price and in a reproducible manner. The very limited control...

    E. Tatarova, A. Dias, J. Henriques, M. Abrashev, N. Bundaleska… in Scientific Reports (2017)

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  5. No Access

    Article

    Deposition of graphene/graphene-related phases on different substrates by thermal decomposition of acetone

    Here we present results on the deposition of graphene and graphene-related phases by chemical vapour deposition (CVD) method. The source of carbon is thermally decomposed acetone (C2H6CO) in Ar main gas flow at d...

    T. I. Milenov, I. Avramova, E. Valcheva, S. S. Tinchev in Optical and Quantum Electronics (2016)

  6. No Access

    Article

    Hydride Vapour Phase Homoepitaxial Growth of GaN on MOCVD-Grown ‘Templates’

    We report on an improved quality of thick HVPE-GaN grown on MOCVD-GaN ‘template’ layers compared to the material grown directly on sapphire. The film-substrate interface revealed by cathodoluminescence measure...

    T. Paskova, S. Tungasmita, E. Valcheva, E. B. Svedberg… in MRS Online Proceedings Library (2012)

  7. No Access

    Article

    Hydride vapor-phase epitaxial GaN thick films for quasi-substrate applications: Strain distribution and wafer bending

    The strain distribution in thick hydride vapor-phase epitaxial (HVPE)-GaN layers grown on metal-organic vapor-phase epitaxial GaN templates was studied by means of photoluminescence, x-ray map**, and lattice...

    T. Paskova, V. Darakchieva, E. Valcheva, P. P. Paskov… in Journal of Electronic Materials (2004)

  8. No Access

    Article

    Strain evolution and phonons in AlN/GaN superlattices

    AlN/GaN superlattices (SLs) with different periods grown on GaN buffer layers were studied by infrared spectroscopic ellipsometry (IRSE), Raman scattering (RS) and highresolution reciprocal space map** (RSM)...

    V. Darakchieva, P. P. Paskov, M. Schubert, E. Valcheva… in MRS Online Proceedings Library (2003)

  9. Article

    Hydride Vapour Phase Homoepitaxial Growth of GaN on MOCVD-Grown ‘Templates’

    We report on an improved quality of thick HVPE-GaN grown on MOCVD-GaN ‘template’ layers compared to the material grown directly on sapphire. The film-substrate interface revealed by cathodoluminescence measure...

    T. Paskova, S. Tungasmita, E. Valcheva… in MRS Internet Journal of Nitride Semiconduc… (2000)

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  10. No Access

    Chapter

    Electron State Symmetries and Optical Selection Rules in the (GaAs)m(AlAs)n Superlattices Grown along the [001], [110], and [111] Directions

    Recently, using the method of induced band representations of space groups, the full electron state symmetries and the selection rules for optical transitions in the (GaAs)m(AlAs)n superlattices (SL’s) were studi...

    Yu. E. Kitaev, A. G. Panfilov, P. Tronc… in Advanced Electronic Technologies and Syste… (1997)

  11. Article

    Characterization of MOVPE-Grown GaAs layers by C—V analysis

    T. Paskova, R. Yakimova, E. Valcheva, K. Germanova in Applied Physics A (1993)

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  12. No Access

    Article

    Characterization of MOVPE-grown GaAs layers by C-V analysis

    A computer simulation study of the capacitance of a surface space charge layer in undoped n-GaAs grown by metalorganic vapour phase epitaxy is presented. The effect of the deep donor level EL2 on the surface capa...

    T. Paskova, R. Yakimova, E. Valcheva, K. Germanova in Applied Physics A (1993)

  13. No Access

    Article

    Study of the thermodynamics of adsorption of hydrolyzed modified polyacrylnitrile

    The thermodynamics of adsorption has been studied of hydrolyzed modified polyacrylnitrile (HMP) in water solutions with a concentration ranging from 0.25 g/l to 2.00 g/l on bleached sulphate and unbleached and...

    M. Nedeltscheva, S. Bencheva, E. Valcheva, V. Valchev in Colloid and Polymer Science (1987)

  14. No Access

    Article

    Investigating the kinetics of the adsorption process of polyamideamine on cellulose

    The kinetic dependences have been investigated of the adsorption process of polyamideamine on monocarboxyl cellulose, bleached sulphate cellulose pulp of softwood and bleached sulphite cellulose pulp of hardwo...

    M. Nedeltscheva, S. Mladenova, E. Valcheva in Colloid and Polymer Science (1985)