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  • 1
    Electronic Resource
    Electronic Resource
    Optical characterization of ZnSe/ZnSxSe1−x superlattices pseudomorphically grown on GaAs(100) substrates by molecular beam epitaxy (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2709-2713 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This article presents optical characteristics of ZnSe/ZnS0.12Se0.88 strained-layer superlattices (SLs) with ZnS0.06Se0.94 buffers pseudomorphically grown on GaAs(100) substrates by molecular beam epitaxy. The SL samples exhibit strong blue luminescence. The main emission peaks in photoluminescence spectra can be attributed to the free exciton transitions between lowest electron subband and ground heavy-hole subband of ZnSe wells. The temperature dependence of PL was investigated in detail. The experimental results of temperature dependence of peak positions and linewidths (FWHM) were fitted to the theoretical calculations, based on Varshni's formula and broadening model. The activation energies of the samples were derived from the temperature dependence of PL intensities. The effects of strain and quantum confinement in ZnSe/ZnS0.12Se0.88 strained-layer SLs with different well thicknesses of 30, 60, and 120 A(ring) were studied by experiments and theoretical calculations. Theoretical calculations and experimental observations are in reasonable agreement. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358739
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  • 2
    Electronic Resource
    Electronic Resource
    Orientation dependence of strained ZnSe/ZnS(h11) single quantum well luminescence (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 4272-4278 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pseudomorphic ZnSe/ZnS single quantum well (SQW) structures have been grown on GaP substrates with high Miller indices. Samples with different crystallographic axis, grown under similar experimental conditions, exhibit different thicknesses, since the growth rate of a crystal facet is axis dependent. The optical properties of ZnSe/ZnS(h11) single quantum wells have been successfully related to the axis orientation through a finite square well potential model. Optical transitions in ZnSe SQWs are dominated by the axis dependence of the heavy-hole effective masses. Furthermore, calculations concerning the piezoelectric effect show that the quantum confined Stark effect is almost negligible for 1–2 monolayers thick wells. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367185
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  • 3
    Electronic Resource
    Electronic Resource
    Electronic states in ZnSe/ZnTe type-II superlattice studied by capacitance transient spectroscopy (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 3402-3407 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the electronic states in N-doped ZnSe/ZnTe type-II superlattice (SL) by deep level transient spectroscopy (DLTS) and isothermal capacitance transient spectroscopy (ICTS). The capture and emission processes of holes between a miniband of the SL and the valence band of ZnSe barrier were investigated. From the analysis of DLTS and ICTS spectra, the activation energy for the hole emission from the miniband energy level was determined to be 0.28±0.03 eV, which is consistent with a theoretical value (0.25 eV) of the band offset between the ZnSe/ZnTe SL calculated based on the Kronig–Penney model. A deep level with an activation energy of 0.48±0.03 eV was observed and has been assumed to originate from an interface defect in the SL region. A deep level located at 0.54±0.03 eV above the valence band of ZnSe was also observed in the ZnSe capping layer. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365655
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  • 4
    Electronic Resource
    Electronic Resource
    Localization and thermal escape of excitons in ultrathin ZnSe/ZnS single quantum wells linked to interfacial ZnSe quantum slabs (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 6028-6033 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ultrathin ZnSe/ZnS single quantum well structures have been grown by molecular beam epitaxy, on GaP substrates with high Miller indices. The optical properties of pseudomorphic ZnSe/ZnS single quantum wells have been investigated by conventional optical methods. Power-dependence and temperature-dependence measurements show that structural disorder plays an important role in ZnSe/ZnS ultrathin single quantum wells. The luminescence emission is the collective response of a group of local potentials with quantum dotlike characteristics. Consequently, the luminescence peak is the convolution of individual narrow lines. In addition, the luminescence spectra are dominated by a thermal escape of carriers when investigating the temperature dependence. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367471
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of hydrostatic pressure on strained CdSe/ZnSe single quantum wells (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2267-2269 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of hydrostatic pressure on the quantum confined transition in CdSe/ZnSe single quantum wells grown by molecular beam epitaxy has been studied by low-temperature photoluminescence measurements. Samples with layer thicknesses of CdSe from 1 to 4 monolayers were used. Strong excitonic emissions associated with the lowest Γ-Γ interband transitions were observed in these highly strained quantum well samples. The pressure coefficients of the interband transitions are found to depend on well thickness with the numerical value decreasing as the well width increases. Pronounced sublinear pressure dependence of the excitonic emissions was observed in the samples with 3 and 4 monolayer CdSe wells, indicating the degradation of the samples due to strain relaxation. Our results suggest that the critical thickness for the CdSe layer pseudomorphically grown on ZnSe is less than 4 monolayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111640
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  • 6
    Electronic Resource
    Electronic Resource
    Observation of quantum dot-like behavior of GaInNAs in GaInNAs/GaAs quantum wells (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2337-2339 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a quantum dot-like behavior of GaInNAs due to composition nonuniformity of N and In in GaInNAs/GaAs quantum wells (QWs). Images of cross-sectional transmission electron microscopy show that the wells of both Ga0.7In0.3As/GaAs and Ga0.7In0.3N0.02As0.98/GaAs are undulated due to lateral variations in strain. This effect is more pronounced in the N-containing QWs due to nonuniform In and N concentrations. Rapid thermal annealing causes a blueshift of the photoluminescence (PL) peak, and results in a splitting of the as-grown broad PL emission into two peaks. The In and N composition fluctuation after annealing becomes predominantly bimodal. The low-energy PL peak is attributed to excitons localized at deep levels, which are originated from In- and N-rich regions in the wells acting as quantum dots (QD). The high-energy peak PH is likely due to the excitons of the 2D QWs. To reduce the local strain, N atoms are preferentially localized in the In-rich regions, so the separation between these two peaks increases with increasing N concentration. Increasing excitation intensity results in a significant blueshift for PL and little blueshift for PH, due to the easier band filling of the localized QD states than QW states. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123843
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  • 7
    Electronic Resource
    Electronic Resource
    Optical properties of highly strained CdSe/ZnSe quantum wells (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 5699-5704 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a study of the optical properties of highly strained CdSe/ZnSe quantum well system. A variety of CdSe/ZnSe samples containing single quantum well or multiple quantum wells grown by molecular beam epitaxy has been studied by using low-temperature photoluminescence (PL), photoluminescence excitation, and photoreflectance measurements. The strong PL signals associated with excitonic emissions from the samples show that the CdSe/ZnSe heterostructure system is promising in the development of laser diodes and light-emitting diodes operating in the blue-green range. Linewidth narrowing of PL spectra with decreasing well width is observed and attributed to alloy formation at the interface due to lateral interdiffusion. The PL signal intensities and the pressure coefficients of interband transitions are also found to depend on the well width, which can be explained in terms of strain relaxation induced misfit dislocations and the critical thickness in the heterostructure system. Our results suggest that the critical thickness for a CdSe layer coherently grown on ZnSe is less than four monolayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354185
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  • 8
    Electronic Resource
    Electronic Resource
    Numerical simulation of incompressible Navier-Stokes and Euler equations to the vortical flow about a delta wing (1997)
    Springer
    Acta mechanica 122 (1997), S. 21-31 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary An algorithm based on the method of artificial compressibility is used to solve the incompressible Navier-Stokes and Euler equations in 3D generalized curvilinear coordinates. The choice of the pseudocompressibility parameter β is discussed and a function form of β which accelerates the convergence effectively is presented. Numerical simulation of the vortical flow about a 70° delta wing is made by both Euler and Navier-Stokes methods. Comparison of the computed results and the experimental data indicates that the Euler method can capture the global flow feature, i.e., separation from the sharp leading edge and the formation of the leading-edge vortex; the Navier-Stokes method depicts not only the flow features captured by the Euler method, but also the boundary layer effects and specifically the secondary separation induced by the leading-edge vortex on the wing upper surface. Thus, the Navier-Stokes method shows a much improved correlation with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01181987
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  • 9
    Electronic Resource
    Electronic Resource
    An inverse integral 3D compressible boundary layer method and coupling with transonic inviscid solution (1991)
    Springer
    Acta mechanica 89 (1991), S. 187-208 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A new velocity profile, which has a simple expression and agrees well with experimental data in a wide range, is proposed in the present paper. Based on this profile, the governing equations of the 3D compressible inverse boundary layer method are deduced. The steady transonic viscous flow around a 3D wing can be calculated as follows: the inviscid flow is calculated by using nonisentropic full potential equation; the viscous flow is calculated by using present boundary layer method; the viscous and inviscid solutions are coupled by using semi-inverse method. Numerical results agree well with the experimental data and required computer resources are less, so that it has broad prospects in the engineering application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01171255
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  • 10
    Electronic Resource
    Electronic Resource
    The computation of transonic analysis and design (1989)
    Springer
    Acta mechanica 78 (1989), S. 81-94 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In this paper a new high efficiency C-O grid coupled with the potential flow solver based on the finite volume technique is given. It significantly reduces the CPU time and increases the computational efficiency. In order to improve the accuracy of traditional potential method a shock point operator is used to account for entropy correction. Some calculated results of 2D inviscid, viscous/inviscid interaction and 3D inviscid flow indicate that nonisentropic potential method produces results closer to Euler solution as well as experimental data, while its computational efforts are nearly the same as the usual isentropic potential method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01174002
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