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  1. No Access

    Article

    Thermal Processes in Electron-Beam Treatment of Metals

    An amended quasi-stationary model of heat transfer in a metallic ingot hardening in a water-cooled crucible after electron-beam melting and refining of the metal is suggested. The processes of heat transfer an...

    K. Vutova, V. Donchev, V. Vassileva, G. Mladenov in Metal Science and Heat Treatment (2014)

  2. No Access

    Article

    GaAs Photodetector for X-ray Imaging

    We describe briefly a cheap and non polluting technique to grow epitaxial GaAs layers, several hundred microns thick, in a matter of hour. Detectors consisting of a p+/i/n+ structure have been realised with these...

    G. C. Sun, H. Samic, V. Donchev, S. Gautrot… in MRS Online Proceedings Library (2011)

  3. No Access

    Article

    Enhancement of the photoluminescence intensity of a single InAs/GaAs quantum dot by separate generation of electrons and holes

    It is demonstrated that the microphotoluminescence (μPL) spectrum of a single InAs/GaAs self-assembled quantum dot (QD) undergoes considerable changes when the primary laser excitation is complemented with an ...

    V. Donchev, E. S. Moskalenko, K. F. Karlsson, P. O. Holtz… in Physics of the Solid State (2006)

  4. No Access

    Article

    Effect of an electric field on the carrier collection efficiency of InAs quantum dots

    Individual and multiquantum dots of InAs are studied by means of microphotoluminescence in the case where, in addition to the principal laser exciting photoluminescence, second infrared laser is used. It is de...

    E. S. Moskalenko, K. F. Karlsson, V. Donchev, P. O. Holtz… in Physics of the Solid State (2005)

  5. No Access

    Article

    An alternative approach to the electronic-structure calculation of crescent-shaped GaAs/AlGaAs quantum wires

    An alternative approach for calculating the bound states energies in crescent-shaped GaAs/AlGaAs quantum wires is proposed. We consider carrier confinement in the X and Y directions separately, taking advantag...

    M. Saraydarov, V. Donchev, K. Kirilov… in Journal of Materials Science: Materials in… (2003)

  6. No Access

    Article

    Longitudinal photoconductivity of GaAs/AlGaAs quantum wires

    The photoconductivity (PC) of undoped GaAs/AlGaAs quantum wires (QWRs) along the wire direction is studied for the first time. The PC spectrum reveals a strong substrate-related background as well as several s...

    V. Donchev, M. Saraydarov, K. Germanova… in Journal of Materials Science: Materials in… (2003)

  7. No Access

    Chapter

    Extrinsic Surface Photovoltage Spectroscopy — An Alternative Approach To Deep Level Characterisation In Semiconductors

    Surface photovoltage (SPV) spectroscopy in the intrinsic absorption energy range has been successfully used to study semiconductor surface and interface states [1–6]. However, simultaneously with the surface stat...

    K. Germanova, V. Donchev, Ch. Hardalov… in Photovoltaic and Photoactive Materials — P… (2002)

  8. No Access

    Article

    Optical determination of interface roughness in multilayered semiconductor structures

    M. Mazilu, V. Donchev, O. Blum, A. Miller in Applied Physics B (1999)

  9. 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)

  10. No Access

    Article

    Time evolution of zero-bias photocurrent in semi-insulating GaAs:Cr

    V. Donchev, K. Germanova in Journal of Materials Science Letters (1996)

  11. No Access

    Chapter

    Optical and Theoretical Assessment of GaAs Quantum Wells Having Superlattices as Barrier Layers

    The replacement of the AlGaAs alloy barriers of a GaAs quantum well (QW) by short period GaAs/AlGaAs superlattices (SLs) is beneficial because the use of SL structures as prelayers suppress the defect diffusio...

    V. Donchev, I. Ivanov, K. Germanova in Devices Based on Low-Dimensional Semicondu… (1996)

  12. No Access

    Article

    On the maximum in hall coefficient temperature dependence in medium-doped n-GaAs

    Hall coefficient and conductivity are measured in a wide temperature interval from 14.5 to 295 K in order to characterize n-type GaAs bulk monocrystals with moderate donor concentration 1017–1018 cm−3. The weak t...

    K. Germanova, V. Donchev, V. Valchev, Ch. Hardalov, I. Yanchev in Applied Physics A (1990)