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  • 1
    Electronic Resource
    Electronic Resource
    Pressure and temperature effects on optical transitions in cubic GaN (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 929-934 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pressure and temperature effects on optical transitions in cubic GaN grown on a GaAs substrate have been studied by photoluminescence (PL) spectroscopy at hydrostatic pressures up to 9 GPa (10 K) and as a function of temperature (10–300 K) at ambient pressure. The dominant emissions at 10 K and ambient pressure are assigned to the bound-exciton transition (zero-phonon line), the donor-acceptor-pair (DAP) emission, and, tentatively, to the first three LO-phonon replicas of the bound exciton. These PL features shift to higher energy with increasing pressure. The pressure coefficients indicate that the observed recombination processes involve states which are closely related to the band edges. Temperature-induced evolutions from bound to free-exciton (FE) transition and DAP emission to free-to-bound transition are resolved. The binding energies of the FE and donor and acceptor levels in cubic GaN have been determined from the temperature and power-density dependence of the PL emission energies. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370826
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  • 2
    Electronic Resource
    Electronic Resource
    Observation of quantum wire formation at intersecting quantum wells (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1956-1958 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first observation of a quantum bound state formed at the junction of two intersecting quantum wells in the shape of a T. The atomically precise T junctions are fabricated by a novel cleaved edge overgrowth process in the AlGaAs/GaAs system. The identification of bound states with energies in excess of 20 meV is made by optical emission and absorption spectroscopy. Such quantum wire states are caused by the unique confinement of the lowest state wave function to the region of the T junction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108375
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  • 3
    Electronic Resource
    Electronic Resource
    Optical properties of modulation-doped quantum wires fabricated by electron cyclotron resonance reactive ion etching (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 237-239 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Modulation-doped GaAs/AlGaAs quantum wires have been fabricated using electron-beam lithography followed by electron-cyclotron resonance reactive ion etching to selectively deplete the electron gas. This technique has the advantages of low damage to the quantum well, strongly anisotropic etching, and reproducible control over the etch depth. The quantum wires exhibit high photoluminescence efficiencies when etched as close as 200 A(ring) to the electron gas. The fundamental gaps show the large optical red shifts associated with strongly spatially indirect transitions. The spacings between one-dimensional subbands determined from inelastic light scattering measurements are larger than 2 meV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110352
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  • 4
    Electronic Resource
    Electronic Resource
    High-gain excitonic lasing from a single InAs monolayer in bulk GaAs (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1433-1435 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of highly efficient laser emission from a single InAs layer with an effective thickness of 1.5 monolayers (ML) embedded in bulklike GaAs. Lasing action is obtained at the wavelength of the InAs thin-layer luminescence (870 nm) by cw optical pumping with a threshold power density of 0.9(3) kW/cm2 at 10 K. Gain measurements yield a very high material gain of 1.0(5)×104 cm−1 for the InAs layer when pumped with ∼10 kW/cm2 at low temperatures. The 0 dimensional character of the emission as determined from cathodoluminescence and the absence of band-gap renormalization with increasing pump level speak for an excitonic mechanism of population inversion. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120586
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  • 5
    Electronic Resource
    Electronic Resource
    Ion induced ridge electrons and their diffraction in solid foil targets (1987)
    Springer
    The European physical journal 4 (1987), S. 253-261 
    Details
    ISSN: 1434-6079
    Keywords: 34.50H ; 79.20N ; 61.14F
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present detailed double differential distributions of electrons emitted downstream when 100 and 170 keV protons interact with thin carbon, gold and aluminuum foils and compare them to those obtained with protons and neutral hydrogen projectiles interacting with helium gas. The distributions obtained with the gas target show, besides the well known convoy electron peak produced by capture or loss of electrons into the continuum of the emerging ion, a narrow ridge that is aligned with the beam direction. This ridge, which is attributed to electrons moving in the two Coulomb center potential saddle determined by the target and projectile ions, also appears in the ion-solid electron distributions. A typical solid state effect consists in the appearance of two strong lateral humps which are explained as due to diffraction of the ridge electrons in the three dimensional lattice of the polycrystalline foil material. Contrarily the diffraction of convoy electrons is impeded by their strong correlation to the moving ions. In the case of the Aluminuun target the observed diffraction is typical for Al2O3. This indicates that the observed electrons originate from a thin polycrystalline oxyde layer close to the downstream surface of emission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01436636
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  • 6
    Electronic Resource
    Electronic Resource
    Do solid surface potential barriers retard convoy peak electrons? (1987)
    Springer
    The European physical journal 6 (1987), S. 55-59 
    Details
    ISSN: 1434-6079
    Keywords: 34.50.Hc ; 73.30.+y ; 79.20.Rf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using a coaxial cylindric electron spectrometer and an electrostatic ion energy analyzer in tandem, a direct measurement of the difference of the energy of convoy peak electron and the electron equivalent ion energy of protons emerging from the downstream surface of C, Au and Al foils is performed in the proton energy range from 60 to 250 keV. This measurement is made possible using the accepted evidence that for a gas target these energies are equal. It is found that also for the beam foil convoy peak electrons, within an experimental average uncertainty of about ±0.1 eV, there is no difference between these energies. If one accepts that the origin of convoy electrons is from inside the solid, the conclusion is that no retardation by the solid surface potential barrier, which is of the order of a few eV, is observed. This is attributed to the strong electron-ion Coulomb interaction which almost completely overshadows the force exerted on the electron by the field of the surface barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01436998
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