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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 584-591 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The chemical composition of the surfaces and interfaces of NbN-MgO-NbN trilayers has been studied by x-ray photoelectron spectroscopy during the fabrication of the trilayer without breaking the vacuum. The NbN and MgO layers were prepared by rf magnetron sputtering. The results of the chemical analysis have been correlated to the electrical characteristics of the completed NbN-MgO-NbN tunnel junctions. During the deposition of the MgO barrier layer the presence of a high amount of energetic oxygen ions and atoms in the sputtering plasma results in a strong plasma oxidation of the NbN base electrode and, hence, in mixed Nb2O5-MgO barriers. The oxygen ions and atoms are generated by the dissociation of the target material and the water of the background pressure. Their amount was found to increase with increasing argon pressure during the MgO sputtering process. Also, adsorption layers of hydroxides on the MgO-target result in the formation of an uncontrollable amount of niobium oxide components at the interface between the NbN base electrode and the MgO barrier. The current-voltage characteristics of tunnel junctions with such barriers show large subgap leakage currents. Pure MgO barriers can be prepared by reducing the oxygen bombardment of the NbN films during the MgO deposition. Pure MgO barriers are oxygen deficient and easily adsorb hydroxides. These hydroxides react with the first layers of the NbN top electrode to NbO2 and NbO thereby reducing and broadening the sumgap value of the tunnel junctions. Tunnel junctions with pure MgO barriers of a nominal thickness of less than 2 nm usually have current-voltage characteristics indicative for microshorts. A special annealing procedure of the NbN-MgO bilayers prior to the deposition of the top electrode desorbs the hydroxides, transforms Mg(OH)2 to MgO without forming metallic magnesium and prevents the formation of intermediate layers of niobium suboxides and metallic shorts.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 67 (1945), S. 82-83 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1170-1172 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Laser radiation from GaAs/AlGaAs laser diode arrays of high output power is studied during nano- to millisecond carrier injection in temporally and spectrally resolved emission measurements. A red shift of the multimode emission spectrum by up to 12 nm and a concomitant increase of the total bandwidth are caused by a transient rise of the device temperature by up to 50 K. Spatially resolved experiments reveal a lateral temperature difference of about 2 K between the center and the edge emitters. Different laser array/heat sink combinations are investigated in order to reduce the transient temperature increase. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6135-6144 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: New experimental and theoretical results on TE/TM bistability in 1.3 μm ridge-waveguide InGaAsP/InP bulk lasers at room temperature are presented. Measured polarization resolved light power–current (P–I) characteristics as well as lateral near- and far-field patterns are compared with results from a theoretical model based on the paraxial wave equations for TE- and TM-polarized modes and the diffusion equation for the carrier distribution. The model was numerically evaluated by use of the beam propagation method. The observed TE/TM bistability is explained by the interplay of three different effects: (i) Tensile stress of about 109 dyn/cm2 promotes the TM gain strongly enough to compete with the TE mode. (ii) Improved TM waveguiding due to an enhancement of the effective refractive index near the beam axis caused by carrier depletion with increasing current leads to the onset of TM lasing and TE/TM switching. (iii) The TE/TM transition is accompanied by an abrupt increase of spatial hole burning in the lateral carrier distribution. Because of this nonlinear effect, a lower current is needed to switch the laser back to TE, giving rise to a hysteresis loop in the P–I characteristics and to TE/TM polarization bistability. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2059-2063 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Aging properties of AlGaAs high power laser arrays were monitored by photocurrent (PC) measurements. We demonstrate that this method allows a quantitative analysis of the aging process and provides insight into the microscopic degradation mechanisms. In graded index separate confinement heterostructures, the PC spectra in the spectral range of the laser transition display a substantial current decrease with aging. This is attributed to enhanced rates of surface recombination and defect generation in the graded gap region. In contrast, step index structures exhibit a much smaller change of PC. The PC results are complemented by measurements of low-frequency laser current noise and front facet temperature. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5559-5563 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Temperature profiles in the bulk and at the front facet of a 20 emitter GaAs/AlGaAs double-quantum-well laser array are studied by spatially resolved luminescence and micro-Raman spectroscopy. For optical output powers of about 1 W, the facet temperature of the individual emitters differs by up to 90 K. In contrast, the temperature distribution inside the resonator is highly uniform with temperature differences of less than 2 K. The facet temperature distribution correlates with the near-field intensity pattern of the laser array. Reabsorption of laser emission close to the facet and subsequent surface recombination of the photogenerated carriers represent the main heating mechanism. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 830-832 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The switching dynamics between TE- and TM-polarization states is studied in a strained ridge-waveguide InGaAsP/InP laser that exhibits TE/TM bistability. Using current modulation with frequencies between 50 and 500 MHz, three types of emission are distinguished. With increasing modulation amplitude, the laser runs through a region of TE emission, a range of stochastic switching between TE and TM modes, and a third region of regular polarization switching. The minimum modulation amplitude for regular switching rises strongly with frequency while the respective switching times decrease from about 700 ps at 50 MHz down to 250 ps around 500 MHz, corresponding to gigahertz mode switching.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 12 (1982), S. 0 
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Characterization of the immunological response to Alternaria in sensitive subjects is not complete. We used crossed radioimmunoelectrophoresis (CRIE) to identify antigens in Alternaria extracts reacting with IgE antibody in five patients with Alternaria-sensitive asthma, four with Alternaria-induced rhinitis, three non-allergic asthmatics, and three normal controls. All five Alternaria-asthma patients and three of four Alternaria-rhinitis patients showed IgE binding to a single antigen peak in the CRIE. One patient exhibited specific radio-staining to a second peak, and two other patients had IgE binding to a third antigen. These results suggest an analogy of Alternaria antigens with that found in ragweed pollen extracts, i.e. that IgE antibody is directed against more than one antigen. Using the enzyme-linked immunosorbent assay (ELISA), we found a significant difference (P 〈 0·05, unpaired Student's t-test) in igG binding between Alternaria-sensitive asthmatics and normal controls. There was no apparent difference in IgG binding between untreated Alternaria-sensitive asthmatics and those receiving high-dose immunotherapy.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Bingley : Emerald
    International journal of physical distribution and logistics management 35 (2005), S. 161-176 
    ISSN: 0960-0035
    Quelle: Emerald Fulltext Archive Database 1994-2005
    Thema: Wirtschaftswissenschaften
    Notizen: Purpose - This work seeks to examine how front-line employee performance and interdepartmental customer orientation affect the service, supply chain, and financial performance of US distribution centers. Design/methodology/approach - The authors approached this subject by utilizing works from the supply chain management, services marketing, total quality management, and logistics personnel literature. Surveys were administered in 18 distribution centers across the USA and canonical correlation was employed to test the propositions that front-line employee performance and interdepartmental customer orientation have a positive effect on distribution center service, supply chain, and financial performance. Findings - Findings indicate that high levels of front-line employee performance and interdepartmental customer orientation a positive effect on distribution center service and supply chain performance. The relationship of the two independent variables to distribution center financial performance was only partially supported. Research limitations/implications - The research did not explore how higher levels of front-line employee performance may be obtained and may not be generalizable beyond a distribution center setting. For researchers, the results may be utilized in studies of logistics best practice. Moreover, studies investigating market orientation may find the results useful, as previous contributions have shown interdepartmental customer orientation to be positively related to the market orientation of the firm. Practical implications - The results provide managers with evidence supporting the value of front-line employees and the importance of encouraging departments to service other departments in a customer-oriented manner. Originality/value - This is the first study to detail the relationship between interdepartmental customer orientation and firm performance in a logistical setting, and adds further credence to the importance of front-line distribution personnel in the delivery of quality output.
    Materialart: Digitale Medien
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  • 10
    facet.materialart.
    Unbekannt
    Berlin : Periodicals Archive Online (PAO)
    Orientalistische Literaturzeitung. 73:5 (1978:Sept./Okt.) 447 
    ISSN: 0030-5383
    Thema: Allgemeine und vergleichende Sprach- und Literaturwissenschaft. Indogermanistik. Außereuropäische Sprachen und Literaturen , Ethnologie , Geschichte
    Notizen: Besprechungen
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