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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed a series of photoreflectance measurements in a modulation-doped AlGaAs/GaAs heterojunction containing a high mobility two-dimensional electron gas. Measurements were performed as a function of temperature in the range 2 K≤T≤300 K. We studied the Franz–Keldysh oscillations associated with the E0 transition of both the GaAs and AlGaAs. The fields obtained from these oscillations for both sides of the heterojunction are quite different. Also, the temperature dependence of these fields are radically different. In fact, the temperature dependence of the field in the GaAs side of the modulation-doped heterojunction sample is very similar to that of the field in a single undoped GaAs film deposited on a GaAs substrate, where no two-dimensional electron gas is present. This shows that the field producing the observed oscillations on the GaAs side of the modulation-doped heterojunction sample is not related to the field that confines the two-dimensional electron gas.
    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 71 (1992), S. 5619-5622 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied the light scattering spectra of three molecular beam epitaxy GaAs samples with Si-δ doping. A broad feature appears in these spectra which is similar to that attributed by other authors to resonant Raman scattering by electronic intersubband transitions. By studying the dependence of this emission on exciting laser photon energy we believe that this line is really produced by nonequilibrium luminescence at the E0+Δ0 gap.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5027-5031 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An efficient variational method to solve the two-dimensional Schrödinger equation using a basis set of cubic B splines is introduced. The method, which uses the effective mass theory and the envelope function approximation, is applied to find the energy levels of quantum-well wires of different shapes. Finally, for rectangular wires a very simple method based on a special decomposition of the V(x,y) potential is used to reduce the problem to two one-dimensional equations. This gives very good results even for very narrow wires, where the conventional decomposition V(x,y)=V(x)+V(y) fails.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5946-5949 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An emission band that appears in the high energy side of the photoluminescence spectra of a modulation doped multiple quantum well structure was investigated by means of magneto-photoluminescence and photoluminescence excitation spectroscopy. We show that this emission band is related to the Al0.36Ga0.64As layers of the structure. We analyze the data within the framework of the configuration coordinate model and attribute this photoluminescence band to the recombination of electrons trapped to a new deep center in the alloy and the photogenerated holes. © 1995 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3281-3289 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use photoluminescence and photoluminescence excitation experiments with and without magnetic field to study the electronic properties of InxGa1-xAs/GaAs quantum wells grown on vicinal (001) substrates. We analyze samples of a wide range of In contents (from 17% to 35%) and various misorientation angles (up to 6°). The optical quality of the samples increases with the tilt angle and is explained as mainly controlled by alloy disorder. A fit of the electron-heavy-hole transitions is performed by means of a method which consists of the resolution of a two-dimensional Schrödinger equation and which includes two adjustable parameters: the In surface segregation energy Es and the length ξ in which the hydrostatic pressure becomes biaxial as defined by the Nagai's model [J. Appl. Phys. 45, 3789 (1974)]. For a given angle and In content the differences between the PL peaks of vicinal and nominal samples present a maximum as a function of the well width, a fact which is well explained by our theoretical model. A study of the exciton dimensionality has been also carried out using models that take dimensionality into account in different manners. © 1997 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1781-1783 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Here we present experimental evidence of the strong modification of the CdS photoluminescence when it is embedded in a SiO2 colloidal photonic crystal. When the emitted light matches a forbidden photonic band in the matrix, inhibition of the semiconductor photoluminescence is achieved. In this work we prove the effective control of this effect by means of the photonic lattice parameter of the host. CdS was grown by chemical bath deposition and its quality has been checked employing Raman spectroscopy and x-ray diffraction. Scanning electron microscopy is used to study the morphology of the composite. © 1998 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1148-1150 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, we investigate the optical properties of packed monodisperse silica submicron spheres by means of optical transmission measurements. The results are compatible with a three dimensional face centered cubic order in these solid structures. The lattice parameter of these structures, and therefore their optical properties, can be easily tuned through the sphere size (between 200 and 700 nm) thus covering the whole visible and near infrared spectrum. © 1997 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 4666-4669 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Linear electro-optic effects in zincblende semiconductors are theoretically analyzed by means of a microscopic simple model without any fitting of parameters. Faust–Henry, second harmonic generation, and linear electro-optic coefficients are obtained from the calculation of the derivatives of the susceptibility with respect to electric fields and ionic displacements. Our results for GaP, GaAs, InP, ZnSe, and ZnTe are in satisfactory agreement with the available experimental information.
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2347-2349 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method for obtaining Ge nanocrystals has been developed using the porous structure of zeolite Y as a matrix. Samples were obtained by reduction of GeO2 nanocrystals, previously grown in zeolite α cages, in H2 at 470 °C. This is apparently the lowest GeO2 reduction temperature reported and is probably due to the influence of the host. Ge crystallites so formed present an absorption edge at 2.2 eV, which is shifted ∼1.4 eV with respect to the bulk value. A softening and an asymmetric broadening of the Raman peak were also observed. We can estimate an average diameter of 3 nm for the Ge nanocrystals from both results. © 1996 American Institute of Physics.
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2309-2311 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method to fabricate a diamond structure with a complete photonic bandgap in the near infrared is proposed. The procedure starts by building an opal with body-centered-cubic symmetry composed of two types (organic and inorganic) of microspheres by means of a microrobotic technique. Then, the organic particles may be selectively removed to obtain a diamond structure of inorganic particles. This method can be extended to make diamond inverse opals of silicon with full gap to midgap ratios as large as 13% for moderate filling fractions. © 2001 American Institute of Physics.
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