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  • 1
    Electronic Resource
    Electronic Resource
    Atom-by-atom substitution of Mn in GaAs and visualization of their hole-mediated interactions (2006)
    [s.l.] : Nature Publishing Group
    Nature 442 (2006), S. 436-439 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The discovery of ferromagnetism in Mn-doped GaAs has ignited interest in the development of semiconductor technologies based on electron spin and has led to several proof-of-concept spintronic devices. A major hurdle for realistic applications of Ga1-xMnxAs, or other ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature04971
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  • 2
    Electronic Resource
    Electronic Resource
    Semiconductor physics Relativity on a chip (2004)
    [s.l.] : Nature Publishing Group
    Nature 427 (2004), S. 21-22 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Two great revolutions in physics in the early twentieth century — quantum mechanics and Einstein's relativity — altered how we understand electromagnetism and motion. In the semiconductor-based technologies of modern-day electronics, the motion of electrons and their interactions are ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/427021a
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  • 3
    Electronic Resource
    Electronic Resource
    Condensed-matter physics Nickel probes superconductivity (2001)
    [s.l.] : Nature Publishing Group
    Nature 411 (2001), S. 901-903 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The unusual properties of superconductors arise from the coherent behaviour of electrons when they flow together in pairs. Two key properties for electrons in a superconductor are their negative charge, which normally keeps them apart, and their spin, which can be thought of as a tiny bar magnet, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35082179
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  • 4
    Electronic Resource
    Electronic Resource
    Mid-infrared InAs/GaInSb separate confinement heterostructure laser diode structures (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3283-3289 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Despite recent progress in electronic structure engineering of type-II materials for mid-infrared lasers, suppression of Auger recombination at room temperature has been limited. We present an active region design, consisting of AlAsSb/InAs/GaInSb/InAs/AlAsSb wells separated by an InAs/AlGaSb superlattice, that overcomes this limitation. The 300 K calculated Auger recombination rate in this structure at the optimal lasing density is five times smaller than typical Shockley–Read–Hall (defect-assisted) recombination rates. An integrated separate confinement heterostructure design suitable for this active region is also described. The separate confinement region, which is a lightly doped InAs/AlGaSb superlattice, provides efficient hole transport and injection into the active region. For an estimated nonactive region modal cavity loss of 20 cm−1 and an optical mode width of 1.3 μm, the calculated internal threshold current density is 100 A/cm2 at 300 K for a single quantum well device. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1346657
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of linewidth enhancement factors in midinfrared active region materials (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 7164-7168 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report calculations of the linewidth enhancement factor for five midinfrared active region materials. The linewidth enhancement factors for two type-I quantum wells based on InAsSb are 2.5 and 5.4, which represent a reduction of up to a factor of 2.6 with respect to bulk InAs0.91Sb0.09. However, active region materials based on the type-II, InAs/GaInSb system have linewidth enhancement factors near 1.0, which is a factor of 2–5 reduction compared to the type-I quantum wells. The reduction of the linewidth enhancement factor is associated with both a reduction of the mismatch between the conduction and valence band densities of states and the presence of conduction band dispersion. We describe an additional optimization that is possible in the type-II materials: Carefully placed intersubband absorption features can be used to further reduce the linewidth enhancement factor. We show that linewidth enhancement values as low as 0.3 can be obtained in the type-II superlattices when fabricated into a distributed feedback structure. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372964
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  • 6
    Electronic Resource
    Electronic Resource
    Differential gain, differential index, and linewidth enhancement factor for a 4 μm superlattice laser active layer (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 713-718 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe temporally and spectrally resolved measurements of the material differential gain, differential refractive index, and linewidth enhancement factor for a multilayer superlattice intended for use in midwave-infrared semiconductor lasers. We find good agreement between measured quantities and theoretical predictions based on a superlattice K⋅p formalism. The superlattice was designed for suppression of Auger recombination and intersubband absorption, and we find that the strategies employed in this process result in other characteristics that are desirable in a semiconductor laser gain medium. Specifically, for carrier densities and wavelengths appropriate to threshold in an optimized cavity configuration, this structure has a differential gain of approximately 1.5×10−15 cm2, a value comparable to that reported for near-infrared strained quantum wells. The peak gain and peak differential gain are nearly spectrally coincident, leading to a small value for the differential index. The large differential gain and small differential index result in a linewidth enhancement factor of less than one. This indicates that filamentation in high-power lasers based on this superlattice should be suppressed and that this structure is attractive for use in midwave-infrared lasers designed for spectrally pure operation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370793
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  • 7
    Electronic Resource
    Electronic Resource
    Erratum: "Theoretical performance of midinfrared broken-gap multilayer superlattice lasers" [Appl. Phys. Lett. 70, 3212 (1997)] (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1183-1183 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123494
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  • 8
    Electronic Resource
    Electronic Resource
    Optimization of active regions in midinfrared lasers (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 188-190 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ideal performance of bulk, quantum well, and superlattice active regions for III–V interband midinfrared lasers are compared according to the maximum net gain per unit current density. Based on this figure of merit, which is appropriate for high-power as well as near-threshold operation, InAsSb quantum well active regions should have an order of magnitude lower threshold current than bulk InAs at room temperature. Optimized four-layer superlattices based on the InAs/GaInSb material system, however, should have two to ten times lower threshold currents than the quantum well active regions. Optimal thicknesses for these active regions were evaluated assuming a separate confinement region design. For the four-layer superlattices the optimal thickness is substantially thinner than has been commonly grown: 3 periods rather than 40 periods. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123288
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of interface structure on the optical properties of InAs/GaSb laser active regions (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1683-1685 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present calculations of the fundamental band gap and intervalence absorption in InAs/GaSb materials incorporating both the intrinsic atomistic symmetry of interface bonding and typical compositional gradients near the interfaces. Including these effects quantitatively explains experimentally observed systematic trends in the band gaps of InAs/GaSb superlattices. Calculations of intervalence absorption indicate that the internal loss in laser active regions based on these materials can not be predicted quantitatively without including these effects. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1456238
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  • 10
    Electronic Resource
    Electronic Resource
    Excited-state dynamics and carrier capture in InGaAs/GaAs quantum dots (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3320-3322 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Subpicosecond time-resolved photoluminescence upconversion is used to measure the 12 K first-excited-state dynamics in large InGaAs/GaAs self-assembled quantum dots designed for 1.3 μm diode lasers. A comparison with the ground-state dynamics suggests that energy relaxation occurs in a cascade through the multiple discrete levels with an average interlevel relaxation time of ∼250 fs. Excited-state emission is observed from two distinct populations. Due to the ultrafast relaxation from the excited state to the ground state in dots containing only a single exciton, the excited-state emission is dominated by the fraction of dots that capture more than one electron–hole pair. In this case, state filling in the ground state blocks the ultrafast relaxation channel, thereby enhancing the excited-state emission. While state filling and a random capture process dictate the primary features of the excited-state emission, at low excitation levels we find that the rise time of emission from the excited state is influenced by the much denser population of singly occupied dots. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1418035
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