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Suche nach „[J.] [Goodwin]“ hat 10 Publikationen gefunden
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    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    Thomas Stirner, P. Harrison, W. Hagston, J. Goodwin

    Reply to "Comment on ‘Theoretical investigation of observed magnetic-polaron energies in quantum wells’"

    Physical Review B - condensed matter and materials physics, vol. 53, pp. 2143-2144

    1996

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    J. Goodwin, P. Harrison, W. Hagston, Thomas Stirner

    Dynamical aspects of free exciton magnetic polaron formation in CdTe-Cd1-xMnxTe quantum wells

    Advanced Materials for Optics and Electronics, vol. 3, no. 1-6, pp. 117-125

    1994

    DOI: 10.1002/amo.860030117

    Abstract anzeigen

    Calculations of the energies of magnetic polarons formed by free excitons localised in non-magnetic CdTe wells next to magnetic Cd1 − xMnxTe barriers are presented. A comparison with recent time-resolved spectroscopy results allows insight to the physical aspects governing the dynamics of the formation of the polarons. It is shown that the experimentally measured energy shift is not the polaron energy itself but the difference between this and the change in the exciton binding energy. The latter is calculated within the envelope function approximation and by employing a variational technique. The polaron energy calculation uses a modified version of an approach described by Wolff. The results show that static polaron calculations are not generally reliable and that the exciton–magnetic polaron has to be viewed as a dynamically evolving complex. It is initially energetically favourable for the exciton–magnetic polaron complex to increase its spatial localisation, since the gains in polarisation energy exceed the loss in exciton binding energy. However, thermodynamic considerations suggest that in general saturation of the magnetic ions will not occur.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    P. Harrison, W. Hagston, J. Goodwin, Thomas Stirner

    Effect of interface disorder on the optical properties of CdTe-Cd1-xMnxTe microstructures

    Surface Science, vol. 313, no. 3, pp. 417-426

    1994

    DOI: 10.1016/0039-6028(94)90061-2

    Abstract anzeigen

    High quality CdTe/Cd1−xMnxTe quantum well structures can be routinely grown in the authors' laboratory by molecular beam epitaxy (MBE). At temperatures of ∼ 2 K these structures have optical linewidths ≲ 3 meV for quantum well widths ≲ 20 Å. The present paper shows how information on the nature and extent of the interface roughness in such systems can be deduced from studies of the optical linewidths and Stokes' shifts.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    P. Harrison, W. Hagston, J. Goodwin, Thomas Stirner

    Magnetic field effects in diluted magnetic semiconductors

    Physical Review B - condensed matter and materials physics, vol. 50, pp. 5255-5263

    1994

    DOI: 10.1103/PhysRevB.50.5255

    Abstract anzeigen

    A general formalism for evaluating the effects of the large magnetic exchange interaction between single carriers and the magnetic ions in a diluted magnetic semiconductor, in the presence of an external magnetic field, is developed. In particular, a justification is provided for incorporating a modified Brillouin function into the description of the resulting magnetic effects.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    P. Harrison, W. Hagston, J. Goodwin, Thomas Stirner

    Theoretical investigation of observed magnetic polaron energies in quantum wells

    Physical Review B - condensed matter and materials physics, vol. 50, pp. 5713-5716

    1994

    DOI: 10.1103/PhysRevB.50.5713

    Abstract anzeigen

    Theoretical calculations of free-exciton magnetic-polaron energies in semimagnetic quantum-well structures have been performed. The dependence of the polaron energy on well width, magnetic field, and temperature has been calculated and compared with the experimentally determined values. In this manner conclusions have been drawn with regard to the structural characteristics of the quantum-well systems.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    P. Harrison, W. Hagston, J. Goodwin, Thomas Stirner

    Exciton magnetic polarons in quantum wells

    Journal of Applied Physics, vol. 75, no. 7, pp. 3466-3471

    1994

    DOI: 10.1063/1.356107

    Abstract anzeigen

    Theoretical calculations of free‐exciton magnetic polaron energies in semimagnetic quantum‐well structures have been performed. The dependence of the polaron energy on well width, magnetic field, and temperature has been calculated. Polaron energy calculations in diffused semimagnetic quantum wells show a strong dependence of the polaron energy on the amount of diffusion in the quantum well. Consequently, magnetic polaron energies could be used as a means of measuring the diffusion coefficient.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    P. Harrison, W. Hagston, J. Goodwin, Thomas Stirner, O. Holbrook

    Impurity bound magnetic polarons in diluted magnetic semiconductors

    Physical Review B - condensed matter and materials physics, vol. 50, pp. 5264-5271

    1994

    DOI: 10.1103/PhysRevB.50.5264

    Abstract anzeigen

    Theoretical calculations of magnetic polaron energies resulting from charge carriers bound to donor or acceptor ion sites in diluted magnetic semiconductors have been performed. The dependence of the polaron energy on the magnetic field, the temperature, and the concentration of the magnetic ion has been evaluated. Similarly the effects of central cell corrections on polaron energies have been determined. The calculated values of the polaron energies are compared with experimental results and the implications of the comparison are discussed.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    Thomas Stirner, P. Harrison, W. Hagston, J. Goodwin

    Band gap renormalization and observation of the type I-type II transition in quantum well systems

    Journal of Applied Physics, vol. 73, no. 10, pp. 5081-5087

    1993

    Abstract anzeigen

    Quantum wells (or barriers) are of finite extent (≤100 Å) along the growth direction. Hence, for at least one or two monolayers adjacent to the interface, the corresponding one‐electron potential in the conduction (or valence) band must differ from that appropriate to the bulk material. The present article demonstrates the pronounced effect such short‐range ‘‘interface potentials’’ can have on the transition energies and oscillator strengths in a dilute magnetic semiconductor system undergoing a type I–type II transition in an external magnetic field.

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Vortrag

    J. Goodwin, Thomas Stirner, P. Harrison, W. Hagston

    Dynamical aspects of free exciton magnetic polaron formation in CdTe-Cd1-xMnxTe quantum wells

    Posterpräsentation

    European Workshop on II-VI Semiconductors, Aachen

    1992

    Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Vortrag

    Thomas Stirner, P. Harrison, W. Hagston, J. Goodwin

    Effect of interface disorder on Stokes’ shift and photoluminescence line width in CdTe-CdMnTe microstructures

    IoP Meeting on Strained Layer Structures & Devices, Sheffield, Großbritannien

    1992