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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report here on the reflection high-energy electron diffraction, photoluminescence (PL), and photoluminescence excitation study of the direct growth by molecular-beam epitaxy of one and two monolayers (MLs) of InAs on GaAs. InAs can be grown pseudomorphically up to a thickness of 1 ML, deposition of 2 MLs results in three-dimensional nucleation. In the latter case our results suggest that the first ML is disrupted by the growth of the second. This finding is in contradiction of the Stranski–Krastanov growth mode. A 1-ML InAs quantum well (QW) with GaAs barriers produces intense luminescence at 1.465 eV, whereas for the intended 2-ML InAs QW sample, PL characteristic of InAs clusters with a most probable thickness of 3 MLs is observed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2929-2934 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Patterns on YBa2Cu3O6.87 films, laser written in O2 or N2 atmospheres, and with various writing power densities and scanning speeds, have been studied by Raman scattering. For laser writing in O2 at atmospheric pressure, with low power density and fast scanning speed, it is found systematically that the oxygen content of YBa2Cu3Ox can be reduced. Only when the writing power density is high and the scanning speed is low (e.g., 2.3 mW/μm2 and 1 μm/s), do the laser-irradiated lines in an O2 atmosphere approach full oxygenation (x→7). For laser writing in N2 at atmospheric pressure, the oxygen stoichiometry always decreases, rendering the lines nonsuperconducting. The structural phase transition from orthorhombic to tetragonal can be identified with laser writing in a N2 atmosphere with a writing power density of 1.9 mW/μm2 and a scanning speed of 20 μm/s. The oxygen O(4) line (∼500 cm−1) and the Ba line (115 cm−1) disappear, and the intensity of the Cu(2) line (144 cm−1) rises sharply when the phase transition occurs. This study shows how Raman scattering can be used as a routine technique, which is fast, sensitive, and nondestructive, and is able to measure oxygen content on a fine scale (a few μm) during high-Tc superconductor device processing. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature pump–probe transmission experiments have been performed on an arsenic-rich InAs/InAs1−xSbx strained layer superlattice (SLS) above the fundamental absorption edge near 10 μm, using a ps far-infrared free-electron laser. Measurements show complete bleaching at the excitation frequency, with recovery times which are found to be strongly dependent on the pump photon energy. At high excited carrier densities, corresponding to high photon energy and interband absorption coefficient, the recombination is dominated by Auger processes. A direct comparison with identical measurements on epilayers of InSb, of comparable room-temperature band gap, shows that the Auger processes have been substantially suppressed in the superlattice case as a result of both the quantum confinement and strain splittings in the SLS structure. In the nondegenerate regime, where the Auger lifetime scales as τ−1aug=C1N2e, a value of C1 some 100 times smaller is obtained for the SLS structure. The results have been interpreted in terms of an 8×8 k⋅p SLS energy band calculation, including the full dispersion for both k in plane and k parallel to the growth direction. This is the strongest example of room-temperature Auger suppression observed to date for these long-wavelength SLS alloy compositions and implies that these SLS materials may be attractive for applications as room-temperature mid-IR diode lasers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InAs/InAs0.865Sb0.135 quantum wells are characterized using magneto-photoluminescence. Band- to-band transitions are found at energies lower than the band gaps of either the InAs or the InAs0.865Sb0.135 with photoluminescence emission at wavelengths up to 4.8 μm. By modeling the quantum size shifts of the photoluminescence transitions and their energy shift in a magnetic field, the valence band offset between InAs and In(As,Sb) is deduced to be type II with electron confinement in the In(As,Sb) alloy and hole confinement in InAs. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3324-3326 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Molecular beam epitaxial growth of a normally homogeneous InAs0.5Sb0.5 alloy below 430 °C results in its coherent phase separation into platelets of two different alloy compositions with tetragonally distorted crystal lattices. This produces a "natural'' strained layer superlattice (n-SLS) with clearly defined interfaces modulated in the [001] growth direction. A description of the n-SLS growth mode in InAsSb is outlined, and the optical response of a n-SLS structure, which extends to 12.5 μm−considerably further than that of a homogeneous InAs0.5Sb0.5 layer (8.9 μm)−is reported.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature InAs/InAs1−xSbx strained-layer superlattice light-emitting diodes (x∼8%) are reported that emit at λ∼4.2 μm with an internal efficiency of 2.8%. The structures are grown by molecular beam epitaxy on slightly mismatched InAs substrates and include a strained AlSb barrier layer to prevent electron migration to the dislocated substrate–epilayer interface region. Comparison with a near identical structure grown without the barrier layer indicates a factor of four improvement in device efficiency at room temperature. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3473-3475 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 300 K light-emitting diodes which emit at 5 and 8 μm with quasi-cw output powers of up to 50 and 24 μW, respectively, are reported. The devices have a single molecular beam epitaxy grown InAs/In(As, Sb) quantum well in the active region with a strong type-IIa band alignment giving mid-IR emission at energies up to 64% lower than the alloy band gap. The emission energies are shown to be in good agreement with a k⋅p bandstructure model where Qc, the ratio of the strained conduction-band offset to the band-gap difference between the two strained superlattice components, is found to be ∼2.0. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1902-1904 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a simple model for μ(E), the field dependence of the mobility, in polar semiconductors. The resulting four-parameter expression is based on a streaming motion idea and a catchment model previously applied to layer rigidity in intercalated solids. A fitting parameter p, introduced in the catchment model, is shown to be related to the plasmon screening length. The model is applied to new data for InAs and InSb, and the fit is superior to empirical models of similar complexity. We find that energy loss via pure plasmon or coupled mode scattering is important even for intrinsic InSb. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @historical journal 19 (1976), S. 1-31 
    ISSN: 0018-246X
    Source: Cambridge Journals Digital Archives
    Topics: History
    Notes: In spite of the current renaissance of interest and research in the history of Habsburg Spain, very little of significance has yet appeared in English on the post-Olivares period of Spanish government and policy – the period in which the Spanish monarchy declined from a position of European hegemony to that of a second-rate power, the virtually helpless prey of her continental and maritime adversaries. The nineteenth-century histories of Dunlop and Hume, which interspersed sections of court diaries with superficial, descriptive chronicles of foreign and military affairs, were not substantially improved upon by R. Trevor Davies' (admittedly posthumous) study of Spain in Decline. The more recent I studies by Professors Elliott, Lynch and Domínguez Ortiz tend to be somewhat exiguous on the years following the great crisis of 1640 (albeit to differing extents) whilst displaying a common freshness of approach and presentation. This is quite understandable, since the situation in Spanish historiography itself is not much better. The uniformly dismal, perhaps still humiliating, features of this period are a natural deterrent to study in contemporary Spain. Domínguez Ortiz and Valiente apart, researched monographs are non-existent, and it has been left to the Anglo-Saxons to venture, on a modest scale, into the uncharted territories of administrative and monetary history.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @historical journal 33 (1990), S. 769-785 
    ISSN: 0018-246X
    Source: Cambridge Journals Digital Archives
    Topics: History
    Notes: Cardinal Richelieu's spectacular military intervention in Italy in 1629 plunged his ministry into a desperate crisis from which it only narrowly emerged intact. It marked the definitive departure of France upon the difficult road of outright opposition to the Habsburg hegemony in Europe. This policy – as the cardinal well knew – was in many ways potentially counter-productive, with a risk factor so high that failure might well entail the end, not only of his personal career, but with it the adolescent Bourbon state. Indeed, his initiative had the almost immediate consequence of a rebellious challenge from a prince of the blood and his domestic allies, amounting to a prototype fronde des princes. For decades to come, French society was to be impoverished by the manifold negative impact of war, while political stability was persistently affected by the unrelenting material and ideological pressures of continuous hostilities.
    Type of Medium: Electronic Resource
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