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  • American Institute of Physics (AIP)  (7)
  • American Association of Petroleum Geologists (AAPG)  (3)
  • Geological Society of America (GSA)
  • 1
    Electronic Resource
    Electronic Resource
    High-temperature properties of GaInAs/AlGaAs lasers with improved carrier confinement by short-period superlattice quantum well barriers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2863-2865 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of the carrier confinement on the output characteristics of GaInAs/AlGaAs lasers was investigated. To improve the carrier confinement, AlGaAs/GaAs short-period superlattices were used as quantum well barriers. In comparison to lasers with GaAs barriers the structures with the modified barriers show improved temperature properties at low threshold current densities without deterioration of the internal quantum efficiency (〉95%). High characteristic temperatures (T0) well above 300 K were measured between 20 and 75 °C and laser operation up to 238 °C could be achieved. The large improvement in T0 is mainly attributed to the reduced thermionic emission of carriers out of the quantum well due to the increased barrier height and the carrier reflection above the barrier by the short-period superlattice. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122611
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetic-field-effect three-terminal device based on YBa2Cu3O7−δ grain boundary junctions (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1843-1845 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Three-terminal YBa2Cu3O7−δ thin film devices based on a parallel array of grain boundary Josephson junctions were fabricated. The multiloop superconducting device is controlled by the magnetic field generated by a current Ictrl, which modulates the critical current Ic through the Josephson junction array. For these devices a current gain ranging between 2 at 77 K and 5 at 30 K was obtained. The spatial homogeneity of the device properties was studied by low-temperature scanning electron microscopy and by the determination of the supercurrent correlation function. Comparing the measured and the theoretically expected supercurrent correlation function shows that the device characteristics agree well with those expected from the device geometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356326
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  • 3
    Electronic Resource
    Electronic Resource
    Electric field controllable Josephson junctions of high quality in high-Tc superconductors (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3031-3033 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Three-terminal Josephson junctions, the third terminal of which can be used to control the electronic properties of the device, are the key to a number of exciting device applications of high-Tc superconductors. To this end a novel device structure has been developed, which consists of an inverted metal-insulator-superconductor field-effect transistor into which a bicrystal grain boundary junction is embedded. These devices are excellent Josephson junctions as exemplified by their current–voltage characteristics and the magnetic field dependencies of the critical currents. The critical current of the junctions can be changed by 8% per volt applied to the gate electrode, the gate currents being negligible. Because they are sensitive to electric as well as magnetic fields, the junctions can be controlled by two independent inputs. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115567
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of the critical current density in grain boundary Josephson junctions on a nanometer scale (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2289-2291 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The critical current Ic of YBa2Cu3O7−δ bicrystal grain boundary Josephson junctions (GBJs) have been measured in high magnetic fields up to B=12 T. Even at the highest applied magnetic fields, Ic varied periodically with varying magnetic field. By comparing the envelope of the measured Ic(B) dependencies to model calculations we obtain information on the spatial distribution of the supercurrent density jc on a length scale down to below 1 nm. Our analysis gives clear evidence that jc has spatial inhomogeneities on all length scales down to 1 nm with a probability distribution p(a) for the characteristic length scale a of the inhomogeneities. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113263
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  • 5
    Electronic Resource
    Electronic Resource
    Superconducting transport properties of Bi2Sr2CaCu2O8+x bicrystal grain boundary junctions (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 996-998 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed a detailed study of the superconducting transport properties of Bi2Sr2CaCu2O8+x bicrystal grain boundary junctions (GBJs). The GBJs were fabricated by the deposition of c-axis oriented epitaxial Bi2Sr2CaCu2O8+x films on SrTiO3 bicrystal substrates. The measured resistive transition R(T), the current-voltage characteristics (IVCs), the temperature dependence of the critical current density Jc(T), and the magnetic field dependence of the critical current Ic(B) of the Bi2Sr2CaCu2O8+x GBJs are similar to those observed for YBa2Cu3O7−δ GBJs. However, for the same misorientation angle the magnitude of Jc is almost an order of magnitude smaller for the BSCCO-GBJs. The R(T) dependencies and the IVCs of the BSCCO-GBJs are close to the prediction of the resistively shunted junction (RSJ) model. The Ic(B) dependencies are close to those of large Josephson junctions with overlap geometry. Our results show that BSCCO-GBJs may be useful for cryoelectronic applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109818
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic field dependence of the critical current in YBa2Cu3O7−δ bicrystal grain boundary junctions (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 783-785 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed a detailed study of the magnetic field dependence of the critical current, Ic(B), of YBa2Cu3O7−δ bicrystal grain boundary junctions (GBJs). GBJs with width W much larger than the Josephson penetration depth λJ show Ic(B) dependencies that are close to those of ideal large Josephson junctions with overlap geometry. The Ic(B) dependencies are symmetrical with respect to B=0 and Ic decreases linearly with increasing applied magnetic field for B≤BJ1, where BJ1 is the lower critical field of the GBJ. Furthermore, Ic(B=0) increases linearly with increasing width of the GBJs as expected for Josephson junctions with overlap geometry. From the measured Ic(B) dependencies the temperature dependence of BJ1 and the London penetration depth could be derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108578
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  • 7
    Electronic Resource
    Electronic Resource
    Distribution of the critical current density and flux trapping in YBa2Cu3O7−δ ramp-edge Josephson junctions (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 241-243 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the spatial distribution of the critical current density in YBa2Cu3O7−δ ramp edge Josephson junctions using low-temperature scanning electron microscopy. Applying this technique allows the imaging of the critical current density distribution with a spatial resolution of about 1 μm. Our measurements show that the geometry of the ramp-edge junction eases the trapping of magnetic flux quanta in the YBa2Cu3O7−δ layer covering the ramp edge. These trapped flux quanta result in a spatially inhomogeneous magnetic field parallel to the barrier layer, which in turn results in a spatially modulated supercurrent density and an unusual magnetic field dependence of the critical current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111516
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  • 8
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    Determination of the stable isotope composition and total dissolved solids of Athabasca oil sands reservoir porewater: Part 1. A new tool for aqueous fluid characterization in oil sands reservoirs (2014)
    American Association of Petroleum Geologists (AAPG)
    Details
    Publication Date: 2014-09-27
    Description: We present a new method to determine the total dissolved solids (TDS) concentration and the stable isotope composition of drill-core-derived Porewater in oil sands reservoirs of northeastern Alberta, Canada. The technique described here uses two end-member mixing relationships between the stable isotope compositions of drilling fluids and formation waters from mechanically extracted porewater samples to calculate the formation water TDS, $${\delta }^{2}\mathrm{H}$$ , and $${\delta }^{18}\mathrm{O}$$ values. Analysis of water samples extracted directly from McMurray Formation drill core provides an inexpensive and robust advance in the ability to characterize the properties of reservoir pore waters that can be widely deployed because of the ubiquity of drill-core sampling. Porewater data from three oil sands wells from different locations within the Athabasca region are presented in this study. Water derived from these wells had TDS values of 860 to 45,000 mg/L, $${\delta }^{2}\mathrm{H}$$ values of –172 to –149, and $${\delta }^{18}\mathrm{O}$$ values of –22.4 to –19.3. These values are consistent with regional trends in formation water salinity and stable isotope compositions, and illustrate the wide range of TDS values that can be found in McMurray Formation waters. The ability to characterize aqueous fluids within bitumen-saturated reservoirs is a new development that enables measurement of aqueous fluid properties that is not easily obtained by other sampling means. This methodology provides a tool to understand the origin and movement of reservoir water related to natural groundwater flow, or to anthropogenic influence by steam injection. Novel in situ extraction technologies that use electromagnetic heating systems may also benefit from detailed characterization of aqueous reservoir fluids to accurately determine the properties of the reservoir porewater.
    Print ISSN: 0149-1423
    Electronic ISSN: 0149-1423
    Topics: Geosciences
    Published by American Association of Petroleum Geologists (AAPG)
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  • 9
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    Determination of the stable isotope composition and total dissolved solids of Athabasca oil sands reservoir porewater: Part 2. Characterization of McMurray Formation waters in the Suncor-Firebag field (2014)
    American Association of Petroleum Geologists (AAPG)
    Details
    Publication Date: 2014-09-27
    Description: A new stable isotope approach was used to determine the total dissolved solids concentration and stable isotope composition for oil sands drill core extracted porewater at the Suncor–Firebag oil sands field in northeastern Alberta, Canada. A stable isotope mixing approach was used to correct for contamination by drilling fluids in the porewater samples. The mean isotopic compositions of oxygen ( $${\delta }^{18}\mathrm{O}$$ ) and hydrogen ( $${\delta }^{2}\mathrm{H}$$ ) in water for fluid samples from 12 wells at Firebag were –20.5 ± 1.4 and –157 ± 11, respectively. The mean total dissolved solids (TDS) concentration of the reservoir formation water in 12 sampled wells was 1100 ± 400 mg/L (1). These results suggest that the McMurray Formation water at Firebag is primarily derived from Holocene groundwater recharge, and that the water within the bitumen reservoir is similar to groundwater well samples obtained within the McMurray Formation at Firebag. The results obtained in this study are consistent with regional trends and previously proposed local hydrogeological flow conditions.
    Print ISSN: 0149-1423
    Electronic ISSN: 0149-1423
    Topics: Geosciences
    Published by American Association of Petroleum Geologists (AAPG)
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  • 10
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    Distribution of total dissolved solids in McMurray Formation water in the Athabasca oil sands region, Alberta, Canada: Implications for regional hydrogeology and resource development (2014)
    American Association of Petroleum Geologists (AAPG)
    Details
    Publication Date: 2014-12-31
    Description: Total dissolved solids (TDS) concentrations of 258 Lower Cretaceous McMurray Formation water samples in the Athabasca oil sands region (54 to 58°N and 110 to 114°W) were mapped using published data from recent government reports and environmental impact assessments. McMurray Formation waters varied from nonsaline (240 mg/L) to brine (279,000 mg/L) with a regional trend of high salinity water approximately following the partial dissolution front of the Devonian Prairie Evaporite Formation. The simplest hydrogeological explanation for the observed formation water salinity data is that Devonian aquifers are locally connected to the McMurray Formation via conduits in the sub-Cretaceous karst system in the region overlying the partial dissolution front of the Prairie Evaporite Formation. The driving force for upward formation water flow is provided by the Pleistocene glaciation events that reversed the regional Devonian flow system over the past 2 m.y. in the Athabasca region. This study demonstrates that a detailed approach to hydrogeological assessment is required to elucidate TDS concentrations in McMurray Formation waters at an individual lease-area scale. The observed heterogeneity in formation water TDS and the potential for present day upward flow has implications for both mining and in situ oil sands resource development.
    Print ISSN: 0149-1423
    Electronic ISSN: 0149-1423
    Topics: Geosciences
    Published by American Association of Petroleum Geologists (AAPG)
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