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1

Digitale Medien

Chelyabinsk. Environmental affairs in a Russian city (1993)

Peterson, D. J.

s.l. : American Chemical Society

Environmental science & technology 27 (1993), S. 596-600

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ISSN: 1520-5851

Quelle: ACS Legacy Archives

Thema: Chemie und Pharmazie , Energietechnik

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1021/es00041a002

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2

Digitale Medien

Effect of ion implantation dose on the interdiffusion of GaAs-AlGaAs interfaces (1990)

Kahen, K. B. ; Peterson, D. L. ; Rajeswaran, G.

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

Journal of Applied Physics 68 (1990), S. 2087-2090

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Experimental results of enhanced interdiffusion of GaAs-AlGaAs interfaces are reported. These are obtained by implanting Ar ions at doses ranging from 2×1013 to 5×1014 cm−2 into heterostructure samples followed by rapid thermal annealing at 950 °C for 30 s. The degree of intermixing decreases from the surface up to the projected ion range and is a function of the implantation dose. It is postulated that this variation results from the coalescence of some of the excess vacancies into extended defects, which are then unavailable to assist in the enhanced interdiffusion process. By assuming that the concentration of mobile vacancies at any depth is proportional to the ion's electronic energy loss and inversely proportional to the ion's nuclear energy loss, the calculated intermixing results are shown to be in good agreement with the experimental data.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.346562

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3

Digitale Medien

Properties of Ga vacancies in AlGaAs materials (1989)

Kahen, K. B. ; Peterson, D. L. ; Rajeswaran, G. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 55 (1989), S. 651-653

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Intermixing of AlGaAs-based interfaces is known to be enhanced by capping wafers with a layer of SiO2. Assuming that this enhancement results from the introduction of additional Ga vacancies into the sample, it is possible to obtain the temperature-dependent equilibrium Ga vacancy diffusivity. Experiments are performed whereby SiO2-capped quantum well samples are annealed at temperatures ranging from 800 to 1025 °C. Calculated photoluminescence shifts are compared with the measured spectra, and a relation for the Ga vacancy diffusivity of the form 0.962 exp(−2.72/kBT) cm2/s is obtained. Using this relation, the equilibrium Ga vacancy concentration can be computed via an ensemble Monte Carlo simulation. The resulting expression is 1.25×1031 exp(−3.28/kBT) cm−3.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.101811

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4

Digitale Medien

Detection of surface (∼1 μm) impurity phases in high Tc superconductors (1989)

Cooke, D. W. ; Jahan, M. S. ; Smith, J. L. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 54 (1989), S. 960-962

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We show that thermally stimulated luminescence is an important method for detecting insulating impurity phases that commonly occur in high Tc superconductors. The technique is sensitive to impurity phases at 〈1% level with a probe depth of ∼ 1 μm, which is the region of interest for many superconductor applications. Samples of Y2O3, Y2BaCuO5, YBa2Cu3O6.2, BaCO3, Ba3CuO4, BaCuO2, and YBa2Cu3Ox (x≈7) were investigated. All but the high quality sintered pellets of YBa2Cu3Ox exhibited relatively intense luminescence. The absence of luminescence, and thus of insulating phases, is correlated with low values of rf surface resistance.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.101419

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5

Digitale Medien

Insensitivity of YBa2Cu3O7−x to ionizing radiation (1989)

Clinard, F. W. ; Foltyn, E. M. ; Livak, R. J. ; [weitere]

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

Journal of Applied Physics 65 (1989), S. 5057-5060

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The high-temperature superconductor YBa2Cu3O7−x has been irradiated in a transmission electron microscope to investigate the effect of high doses of ionizing energy on the microstructure of this material. Electrons of energies low enough to avoid knock-on displacement damage (80 and 100 keV) were used to achieve radiation doses of 1×1012 Gy at 115 K and 2×1013 Gy at room temperature. Using the criteria of twin fading and formation of extended defects, no microstructural damage was observed. These results indicate that YBa2Cu3O7−x is extremely resistant to damage by radiolytic processes.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.343426

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6

Digitale Medien

Strength of Terfenol-D (1989)

Peterson, D. T. ; Verhoeven, J. D. ; McMasters, O. D. ; [weitere]

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

Journal of Applied Physics 65 (1989), S. 3712-3713

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The strength of the magnetostrictive material, Terfenol-D, Tb0.27Dy0.73Fe2.0, has been evaluated by measuring the modulus of rupture as a function of the Fe stoichiometry of the compound. It is shown that the strength improves markedly as the Fe concentration decreases from the stoichiometric value of 2.0 in the compound. The increased strength results from the increasing volume fraction of the rare-earth metal phase produced in the Terfenol-D matrix by the solidification process at lower Fe concentrations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.342599

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7

Digitale Medien

High current YBa2Cu3O7−δ thick films on flexible nickel substrates with textured buffer layers (1994)

Wu, X. D. ; Foltyn, S. R. ; Arendt, P. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 65 (1994), S. 1961-1963

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: High current YBa2Cu3O7−δ (YBCO) thick films on flexible nickel substrates with textured buffer layers were fabricated. Highly textured yttria-stabilized-zirconia buffer layers were deposited by using ion beam assisted deposition (IBAD). Pulsed laser deposited YBCO films were not only c-axis oriented with respect to the film surface but also strongly in-plane textured. The in-plane mosaic spread of YBCO films was ∼10°. A critical current density of 8×105 A/cm2 was obtained at 75 K and zero field for thin YBCO films. It was also demonstrated that thick YBCO films with a high critical current and excellent magnetic field dependence at liquid nitrogen temperature can be obtained on flexible nickel substrates by using the textured buffer layers. The result indicates that thick film technology in combination with IBAD buffer layers could be a viable method for fabricating YBCO tapes in long lengths. © 1994 American Institue of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.112830

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8

Digitale Medien

Single depressed-index cladding ridge waveguide laser with a low aspect ratio (1993)

Kahen, K. B. ; Shantharama, L. G. ; Shepherd, J. P. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 62 (1993), S. 1317-1319

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: A novel ridge waveguide semiconductor laser diode is introduced, which contains a single depressed-index cladding layer. Deployment of this layer significantly reduces the transverse beam divergence, while maintaining reasonable values for the optical confinement factor, Γ, and the lateral index step. For lasers with 500 A(ring) active layers and ridge widths of 4 μm, we measured transverse and lateral far-field beam divergences of 16.4° and 8.2°, respectively, and threshold currents of 67 mA for 500-μm-long devices.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.108717

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9

Digitale Medien

High-temperature superconductor Josephson junctions with a gradient Pr-doped Y1−xPrxBa2Cu3O7−δ (x=0.1, 0.3, 0.5) as barriers (1994)

Jia, Q. X. ; Wu, X. D. ; Reager, D. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 65 (1994), S. 2866-2868

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: High-temperature superconductor YBa2Cu3O7−δ based superconducting-normal-superconducting (SNS) Josephson junctions were fabricated using a unique device design. The normal material included a gradient Pr-doped Y1−xPrxBa2Cu3O7−δ layer which was composed of a light doping (x=0.1) next to both YBa2Cu3O7−δ electrodes, a slightly higher doping (x=0.3) towards the center, and a doping concentration of x=0.5 in the middle of the N layer. This design graded the lattice mismatch between YBa2Cu3O7−δ and the N layer, thus avoiding the accumulation of all the lattice strain at one interface. It also results in good chemical, thermal, and structural compatibility between adjacent layers for the desired multilayer structures. The SNS junctions fabricated in this way showed resistively shunted junction current-voltage characteristics under dc bias and Shapiro steps under microwave irradiation at a temperature in the range of 75–87 K. Direct current superconducting quantum interference devices showed a voltage modulation about 5 μV by a magnetic field at liquid nitrogen temperature. © 1994 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.112518

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10

Digitale Medien

Synthesis of epitaxial Pt on (100)Si using TiN buffer layer by pulsed laser deposition (1994)

Tiwari, P. ; Wu, X. D. ; Foltyn, S. R. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 65 (1994), S. 2693-2695

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: High-quality epitaxial Pt films were deposited by pulsed laser deposition on (100)Si using TiN as a buffer layer. The films were (100) oriented normal to the substrate surface with a high degree of in-plane orientation with respect to the major axes of the substrate and buffer layer. An ion beam minimum channeling yield of 39% was obtained for the Pt films, indicating high crystallinity. High-resolution transmission electron microscopy results showed that interfaces between substrate/film and film/film were quite smooth and no perceptible interdiffusion was observed. The epitaxial TiN layer effectively acts as a barrier to impede metal-substrate reaction and helps in good adhesion of the Pt films on (100)Si. This structure is suitable for epitaxial growth of oxide films on Si with an underlying conductive electrode. © 1994 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.112608

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