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  • Articles  (13)
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  • Springer  (13)
  • 1985-1989  (13)
  • Physics  (13)
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  • Articles  (13)
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  • 1
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    Equilibrium dangling bond densities and its related thin-film alloys (1988)
    Springer
    Details
    Publication Date: 1988-08-01
    Print ISSN: 0947-8396
    Electronic ISSN: 1432-0630
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 2
    Electronic Resource
    Electronic Resource
    Integrable and nonintegrable classical spin clusters (1987)
    Springer
    The European physical journal 65 (1987), S. 363-374 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nonlinear dynamics is investigated for a system ofN classical spins. This represents a Hamiltonian system withN degrees of freedom. According to the Liouville theorem, the complete integrability of such a system requires the existence ofN independent integrals of the motion which are mutually in involution. As a basis for the investigation of regular and chaotic spin motions, we have examined in detail the problem of integrability of a two-spin system. It represents the simplest autonomous spin system for which the integrability problem is nontrivial. We have shown that a pair of spins coupled by an anisotropic exchange interaction represents a completely integrable system for any values of the coupling constants. The second integral of the motion (in addition to the Hamiltonian), which ensures the complete integrability, turns out to be quadratic in the spin variables. If, in addition to the exchange anisotropy also singlesite anisotropy terms are included in the two-spin Hamiltonian, a second integral of the motion quadratic in the spin variables exists and thus guarantees integrability, only if the model constants satisfy a certain condition. Our numerical calculations strongly suggest that the violation of this condition implies not only the nonexistence of a quadratic integral, but the nonexistence of a second independent integral of motion in general. Finally, as an example of a completely integrableN-spin system we present the Kittel-Shore model of uniformly interacting spins, for which we have constructed theN independent integrals in involution as well as the action-angle variables explicitly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01303725
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  • 3
    Electronic Resource
    Electronic Resource
    Integrable and nonintegrable classical spin clusters (1988)
    Springer
    The European physical journal 70 (1988), S. 251-268 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This study investigates the nonlinear dynamics of a pair of exchange-coupled spins with biaxial exchange and single-site anisotropy. It represents a Hamiltonian system with 2 degrees of freedom for which we have already established the (nontrivial) integrability criteria and constructed the integrals of the motion provided they exist. Here we present a comparative study of the phase-space trajectories for two specific models with the same symmetry properties, one of which (the XY model with exchange anisotropy) is integrable, and the other (the XY model with single-site anisotropy) nonintegrable. In the integrable model, the integrals of the motion (analytic invariants) can be reconstructed numerically by means of time averages of dynamical variables over all trajectories. In the nonintegrable model, such time averages over trajectories define nonanalytic invariants, where the nonanalyticities are associated with the presence of chaotic trajectories. A prominent feature in the nonintegrable model is the occurrence of very long time scales caused by the presence of low-flux cantori, which form “sticky” coats on the boundary between chaotic regions and regular islands or “leaky” walls between different chaotic regions. These cantori dominate the convergence properties of time averages and presumably determine the long-time asymptotic properties of dynamic correlation functions. Finally, we present a special class of integrable systems containing arbitrarily many spins coupled by general biaxial exchange anisotropy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01318307
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  • 4
    Electronic Resource
    Electronic Resource
    A chemical-bond approach to doping, compensation and photo-induced degradation in amorphous silicon (1986)
    Springer
    Applied physics 39 (1986), S. 243-250 
    Details
    ISSN: 1432-0630
    Keywords: 12.80. Ng
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We propose that during deposition of a-Si:H films a chemical equilibrium is established that relates the density of dangling-bond defects near mid-gap to the densities of electrons and holes in the conduction and valence band states. We develop the appropriate chemical reaction formalism and show that our model allows doping, compensation and photo-induced degradation to be treated within a single and unifying approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617268
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  • 5
    Electronic Resource
    Electronic Resource
    Surface and volume decay processes in semiconductors studied by contactless transient photoconductivity measurements (1988)
    Springer
    Applied physics 46 (1988), S. 77-85 
    Details
    ISSN: 1432-0630
    Keywords: 72.40 ; 73.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Excess charge carrier kinetics in moderately doped pSi wafers were investigated with a contactless transient photoconductivity method, i.e. the time-resolved microwave conductivity (TRMC) method. The surface structure of the wafers was changed by etching and polishing, the volume structure by irradiation with high-energy electrons. Comparison of the photoconductivity decay after excitation by strongly absorbed light and by weakly absorbed light was used to distinguish between surface and volume decay processes. The experimental results deviate from predictions based on a linear surface decay rate. These results are discussed and suggestions are made for the use of transient photoconductivity measurements to characterize semiconductor wafers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615912
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  • 6
    Electronic Resource
    Electronic Resource
    Semi-insulating electrical properties of undoped inp after heat treatment in a phosphorus atmosphere (1989)
    Springer
    Applied physics 48 (1989), S. 315-319 
    Details
    ISSN: 1432-0630
    Keywords: 72.80.Ey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Nominally undoped InP wafers have been annealed in a phosphorus atmosphere under a pressure of about 5 bar at temperatures of 900 °C for about 80 h. It was found that the electrical properties of the samples changed considerably after this treatment. A room temperature resistivity of up to 2×107Ωcm (semi-insulating behaviour) was obtained in the bulk of the samples. The resistivity finally obtained depends on the starting carrier concentration of the untreated samples. The Hall coefficient and Hall mobility have been measured up to 600 °C. The results can be interpreted in terms of a deep electronic level (E A=0.63 ... 0.65 eV below the conduction band). The Hall coefficient was always found to be negative resulting in a Hall mobility of 1.4 to 4.9×103 cm2/Vs. The highest resistivity in nominally undoped bulk InP so far reported in the literature [1] was ϱ=3.6 × 105Ωcm. Therefore, this paper demonstrates for the first time that a really semi-insulating behaviour of ϱ〉107 Ωcm can be achieved for bulk InP with the purity of nominally undoped material (1015 to 1016cm−3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618891
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of H-dilution on the transport properties of doped a-Si1−x Ge x : H alloys (1989)
    Springer
    Applied physics 49 (1989), S. 165-169 
    Details
    ISSN: 1432-0630
    Keywords: 72.20 ; 72.40 ; 73.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper is concerned with the optimization of growth conditions for a-Si1-x Ge x :H alloys. It is shown that H-dilution of source gases selectively improves the band transport of electrons without significantly affecting the recombination center density or the band transport of holes. It is further shown that the beneficial effects of H-dilution are most pronounced in alloys with comparable densities of Si and Ge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616295
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  • 8
    Electronic Resource
    Electronic Resource
    Doping efficiencies of gas-phase and ion-implantation doped a-Si:H (1986)
    Springer
    Applied physics 41 (1986), S. 253-258 
    Details
    ISSN: 1432-0630
    Keywords: 72.80N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We compare the electronic properties of gas-phase and implantation doped a-Si:H films and analyze their properties within the framework of Street's auto-compensation model [1]. We find that this model can consistently explain the varying degrees of sensitivity with respect to doping for differently prepared a-Si:H materials. In agreement with sub-band-gap absorption data our analysis indicates that the density of native dangling bond defects is increased when the film thickness is decreased and when thin films are further subjected to ion bombardment. Considering the temperature dependence of conductivity, we find that the auto-compensation model can provide an explanation for the high-temperature kink in the conductivity of doped a-Si:H films but that it fails to account for the experimentally observed universality of the “Meyer-Neldel-rule” behaviour of the conductivity prefactor in differently prepared and doped a-Si:H films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616046
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  • 9
    Electronic Resource
    Electronic Resource
    On the generation and annealing of dangling bond defects in hydrogenated amorphous silicon (1988)
    Springer
    Applied physics 45 (1988), S. 41-51 
    Details
    ISSN: 1432-0630
    Keywords: 66.3L ; 68.60 ; 72.80N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We show that, through the diffusive re-arrangement of Si-H bonds, the a-Si∶H lattice is able to establish thermal equilibrium between the densities of band tail trapped charge carriers and dangling bond defects. When this equilibrium is disturbed by changes in temperature, carrier injection or illumination, dangling bond defects have to be generated or annealed out via H-diffusion processes. Based on the concept of charge-induced bond breaking, we develop a mathematical formalism for the diffusive re-arrangement of Si-H bonds and show that our formalism can account for a variety of observations that have been made in the context of defect-generation and annealing experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618762
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  • 10
    Electronic Resource
    Electronic Resource
    Quantum spin chains: Simple models with complex dynamics (1987)
    Springer
    The European physical journal 68 (1987), S. 149-159 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The present study highlights some of the complexities observed in the dynamical properties of one-dimensional quantum spin systems. Exact results for zero-temperature dynamic correlation functions are presented for two contrasting situations: (i) a system with a fully ordered ferromagnetic ground state; (ii) a system at aT c=0 critical point. For both situations it is found that the exact results are considerably more complex than has been anticipated on the basis of approximate approaches which are considered to be appropriate and reliable for such situations. A still higher degree of complexity is expected for the dynamics of quantum spin systems which are nonintegrable. The paper concludes with some observations concerning nonintegrability effects and quantum chaos in spin systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304220
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