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1

Digitale Medien

On the origin of Franz–Keldysh oscillations in AlGaAs/GaAs modulation-doped heterojunctions (1991)

Novellino, R. A. ; Vazquez-López, C. ; Bernussi, A. A. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 70 (1991), S. 5577-5581

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.350170

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2

Digitale Medien

Nonequilibrium luminescence at the E0+Δ0 gap in GaAs with Si-δ doping (1992)

Mestres, N. ; Cerdeira, F. ; Meseguer, F. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 71 (1992), S. 5619-5622

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.350492

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3

Digitale Medien

Electronic energy levels of quantum-well wires (1993)

Sánchez-Dehesa, J. ; Porto, J. A. ; Agulló-Rueda, F. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 73 (1993), S. 5027-5031

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.353772

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4

Digitale Medien

New AlxGa1−xAs related deep luminescence observed in modulation doped quantum wells (1995)

Plentz, F. ; Meneses, E. A. ; Meseguer, F. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 77 (1995), S. 5946-5949

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.359176

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5

Digitale Medien

Optical studies of highly strained InGaAs/GaAs quantum wells grown on vicinal surfaces (1997)

López, C. ; Mayoral, R. ; Meseguer, F.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 81 (1997), S. 3281-3289

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.364162

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6

Digitale Medien

CdS photoluminescence inhibition by a photonic structure (1998)

Blanco, A. ; López, C. ; Mayoral, R. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 73 (1998), S. 1781-1783

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.122280

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7

Digitale Medien

Photonic crystal properties of packed submicrometric SiO2 spheres (1997)

Míguez, H. ; López, C. ; Meseguer, F. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 71 (1997), S. 1148-1150

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.119849

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8

Digitale Medien

Linear electro-optic effects in zinc blende semiconductors (1985)

Hernández-Cabrera, A. ; Tejedor, C. ; Meseguer, F.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 58 (1985), S. 4666-4669

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.336240

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9

Digitale Medien

Low-temperature synthesis of Ge nanocrystals in zeolite Y (1996)

Miguez, H. ; Fornés, V. ; Meseguer, F. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 69 (1996), S. 2347-2349

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.117520

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10

Digitale Medien

Opal-like photonic crystal with diamond lattice (2001)

García-Santamaría, F. ; López, C. ; Meseguer, F.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 79 (2001), S. 2309-2311

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1406560

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