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  • 1990-1994  (17)
  • 1985-1989  (14)
  • 1970-1974  (2)
  • 1930-1934  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Photoluminescence line shape of excitons in GaAs single-quantum wells with and without heterointerface ordering (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1488-1491 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The photoluminescence line shape of excitons at low temperatures is investigated in GaAs single-quantum wells grown by molecular-beam epitaxy with and without intentional heterointerface ordering. From the study of the excitation density dependence in the range between 1015 and 1017 cm−3, it is found that the inhomogeneous linewidth is significantly affected by band-filling effects of intrinsic defect states spatially localized in the wider wells. In the sample with heterointerface ordering the band-filling effects are directly identified by observation of saturation of the localized excitonic emissions, which are split as a result of increased spatial coherence of the excitonic states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344406
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  • 2
    Electronic Resource
    Electronic Resource
    Implosion-driven hypervelocity accelerator (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5254-5256 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A hypervelocity accelerator has been developed utilizing the extreme condition produced by the collapse of the cylindrical imploding shock wave. The cylindrical shell of the explosive is detonated by the explosion of rows of copper wires bound around it. The wire explosion is caused by the application of an impulsive electric current. The energy concentrated at the implosion center is imparted to the projectile accelerating it. The launch velocity of 1.2 km/s has been attained for a 2 g launched weight with a 60 g explosive (PETN: pentaerythritoltetranitrate). A further increase of the launch velocity is expected by increasing either the explosive thickness or the height of the cylindrical shell within practical limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350585
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Numerical simulation of cylindrical converging shocks in solids (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2605-2611 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cylindrically converging shock waves in solids have been analyzed by the random choice method (RCM). A Riemann solver for fluidlike solids with the Grüneisen-type equation of state is constructed and incorporated into the RCM. It is then applied to the cylindrical shock tube problems for solid copper with driving pressures of 20 and 200 GPa. The numerical results are compared with those of the finite difference method (FDM). The shock speed is smaller and the discontinuity at the shock front is smeared out due to the artificial viscosity in the FDM calculation. Spatial distributions of pressure, density, and particle velocity calculated by the RCM show that the steepness at the shock front is maintained both in the converging and reflecting stages. It is shown that the pressure on the shock front and the total energy contained in the central circular area are much larger in the reflecting stage than in the focusing stage. The dimensional analysis has shown that the similarity solution exists; however the numerical result shows that the flow does not fall within the similarity regime in the region of calculation. It suggests that the self-similar flow is only limited in extreme proximity to the axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351560
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Radiative properties of a highly excited quantum well (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1485-1487 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study by time-resolved luminescence, the radiative recombination from a single quantum well placed inside a graded confinement structure. We are able to produce a cold (T〈50 K), high-density (5×1011〈N〈5×1012 cm−2) plasma. We compare our spectra with usual lineshape fitting procedures and give evidence for the shortcomings of such an analysis. We detail the consequences of the present work for the determination of band-gap renormalization, the conservation of k-selection rule, and the measurement of the radiative recombination rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105204
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Explosive-driven cylindrical imploding shocks (1990)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 266-273 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cylindrical imploding shocks are analyzed numerically. The shocks are supposed to be generated by detonating cylindrical explosive shells. Detonations are assumed to be initiated either from the inner or the outer surface of the shells. Explosive shells of different thicknesses are compared. The conversion mechanism of the chemical energy of explosives into gas energy is investigated. In the implosion stage general features of the flow near the shock front are much the same between two different initiations. The same is also true among different explosive thicknesses. However, in the reflection stage after the shock is reflected from the axis, thicker explosives produce higher pressure and temperature near the axis. The difference in the initiation method does not make a very noticeable difference, even in the reflection stage. Shock trajectories, temperatures at the shock front, and evolutions of the pressure at a fixed point are compared between numerical and experimental results. Agreements between the two results are close.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857775
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Observation of free excitons in room-temperature photoluminescence of GaAs/AlGaAs single quantum wells (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 675-677 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Observation of free excitons is reported in room-temperature photoluminescence of nominally undoped GaAs/AlGaAs single quantum wells grown by molecular beam epitaxy. A comparative study with parallel-conduction photocurrent spectroscopy shows that a sharp luminescence peak with a linewidth of 14 meV observed for the 6.1-nm-wide well coincides within 2 meV with the n=1 heavy-hole free-exciton resonance line at excess carrier densities less than 1017 cm−3. Excitonic decay channels dominate the luminescence spectrum even at room temperature as a result of quantum confinement effects, although photogenerated carriers are also provided for photocurrents by exciton dissociations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99847
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Electro-optical multistability in GaAs/AlAs superlattices at room temperature (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 605-607 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the optical absorption properties of a GaAs/AlAs short-period superlattice at room temperature in an electric field perpendicular to the layers. Several pronounced optical transitions related to Wannier–Stark localization are observed indicating a coherence length of at least five superlattice periods. These transitions produce multiple regions of negative differential photoconductivity which are used to realize a multistable self-electro-optic effect device.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102711
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  • 8
    Electronic Resource
    Electronic Resource
    Carrier trapping in single quantum wells with different confinement structures (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 226-228 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The trapping efficiency and trapping dynamics of photoexcited carriers in GaAs/AlGaAs single quantum wells with different confinement structures are examined at low temperature by means of picosecond luminescence as well as photoluminescence excitation spectroscopy. The trapping efficiency is 100% only in graded-index separate confinement heterostructures with a linear band-gap profile. The lower trapping efficiency of other confinement structures is due to radiative and nonradiative recombination in the confinement layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98456
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Capture of photoexcited carriers by a laser structure (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2646-2648 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The capture of photoexcited carriers in different laser structures is investigated by subpicosecond luminescence spectroscopy. The capture time at 20 and 80 K is monitored by the decay of the luminescence of the confinement layers. It is found to range between 2 and 3 ps for both linear and parabolic grading, and to be much longer in nongraded structures. The improvement of the capture in the case of graded structures is due to the quasi-electric field experienced by the carriers, and might allow the devices to run at much higher frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101962
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  • 10
    Electronic Resource
    Electronic Resource
    Linear polarization effects in anisotropic photoemission from GaAs/AlAs short-period superlattices (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1717-1719 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By investigating the linear polarization dependence of intrinsic emissions from undoped GaAs/AlAs short-period superlattices at room temperature, it is shown that a dominating peak observed in the normal emission spectra is due to the free-carrier recombination associated with the lowest electron to mixed-hole subbands with an unexpectedly large light-hole character instead of with the lowest electron to pure heavy-hole subbands expected in an ideal superlattice. Origins of the extensive valence-band mixing in the synthesized superlattices are discussed in relation to microscopic fluctuations in the layer thicknesses observed in the transmission electron microscope lattice image.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98554
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