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  • Artikel: DFG Deutsche Nationallizenzen  (11)
  • 1990-1994  (11)
Datenquelle
  • Artikel: DFG Deutsche Nationallizenzen  (11)
Materialart
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3365-3369 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A new approach to analyze the transport characteristics of resonant tunneling structures has been developed. It is shown that the Fermi-level Ef position per se, the temperature variations of the Fermi-level, the effective mass, and the mobility, have important influences on the resonant tunneling transport properties. Both calculations and experiments have shown very different features for heavy-hole and light-hole resonant tunneling in SiGe/Si resonant tunneling structures. These different features can for the first time be explained coherently. The calculated subband energy at current resonance can be much higher or lower than the Fermi level and the peak current can decrease or increase with temperature, depending on the device structure, the carrier type, and the working conditions. The calculations have predicted an interesting result that, in the low-temperature region, the valley current for the first heavy-hole resonance decreases with temperature, and that is confirmed by our experiments. The calculated temperature dependences of heavy- and light-hole transport, such as peak and valley currents/voltages and their variations with the well width, agree very well with our observations and other published results.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3859-3864 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: To understand the nature of resonant tunneling in triple-barrier/double-quantum-well structures, we have investigated the properties of transmission probability TT of such structures with use of the transfer-matrix method. The transfer matrix of the middle barrier is calculated to analyze the amplitude decay, the phase shift, and the coupling effects that are induced between the two quantum wells. The dependencies of TT and the splitting of the resonant peaks on the middle-barrier thickness, the well width, and the symmetry of the structures are calculated. The origin of the transmission resonance and the resonant condition for symmetric (equal well widths) and asymmetric structures are discussed. The variations of TT with the applied voltage are also analyzed. The calculation results lead to some suggestions on how to design triple-barrier structures with improved performance.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 738-740 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Temperature effects on current transport and the negative differential resistance for SiGe/Si and GaAlAs/GaAs resonant tunneling structures (RTS) have been studied, and the maximum working temperature Tm has been estimated. The calculations show that decreases in the carrier effective mass, well width and barrier thicknesses, lead to better temperature characteristics, implying higher peak current and larger peak-to-valley ratio (PVR) at higher temperature. These results are consistent with our experiment on SiGe/Si RTSs and other published experiments. The crucial role of nonresonant tunneling current Jnon in temperature effects for current transport is emphasized. Suggestions for optimizing RTS design to increase its Tm and PVR are discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2500-2502 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have investigated the resonant tunneling feature variations with temperature in molecular beam epitaxy grown strained Si0.78Ge0.22/Si double-barrier structures with different well width w and spacer thickness LS. Both w and LS have strong effects on the temperature characteristics of the peak current JP, the valley current JV, and the current peak-to-valley ratio (PVR). When w is reduced, both JP and JV are greatly increased. The resonant tunneling devices (RTDs) also have better temperature stability and PVR decreases slower. The RTD with larger LS has higher peak current. Beside w and LS, the quasi-Fermi level position has a very important influence on the resonant tunneling feature variations, which is stressed in the present work.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Biochemistry 31 (1992), S. 8384-8388 
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 113 (1991), S. 4698-4700 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 611 (1990), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 17 (1994), S. 0 
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— The local stress/strain approach has been used to predict the fatigue lives of notched composite components. The method was based on a microstress analysis and the application of a multiaxial fatigue parameter incorporating the alternating strain components on the critical plane. This parameter was able to correlate the fatigue lives obtained under a variety of multiaxial loading and geometrical configurations, enabling a generalized fatigue life curve to be determined on the basis of limited experimental data.The ability of the multiaxial fatigue parameter to relate the fatigue behaviour of composites was illustrated by predicting the locations of crack initiation sites in a unidirectional silicon carbide fibre reinforced titanium plate containing a circular hole tested under constant amplitude cyclic loading. The same approach was also successfully employed to predict the fatigue lives of graphite reinforced epoxy composite tubes with circular holes tested under several combinations of cyclic tension and torsion.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Archives of dermatological research 282 (1990), S. 183-187 
    ISSN: 1432-069X
    Schlagwort(e): Henoch-Schönlein purpura ; Complement ; Cytolysis ; Endothelial cell damage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The present study using direct immunofluorescence with monoclonal antibodies to C5b-9 complex-related antigens was undertaken to determine whether complement activation in Henoch-Schönlein purpura (HSP) causes assembly of the membrane attack complex of complement (MAC) in skin and nephritis lesions. The deposition of C5, C6, C7, C8, C9, and C5b-9 neoantigens was noted in the vascular walls of papillary dermis and/or subpapillary dermal plexus of the vessels in 11 out of 15 patients with HSP. Their presence in vessel walls indicates complement activation which leads to terminal complement activation. There were small deposits of S protein at the same sites in three of the 11 skin specimens. Thus, the majority of C5b-9 demonstrated in HSP skin was the cytolytically active C5b-9 complex, MAC. Granular deposits of C5b-9 related antigens without S protein were also found in the capillary walls and mesangium of the glomeruli of two out of four specimens from patients with HSP nephritis; in the other two S protein was colocalized with the deposition of C5b-9. The results of the present study indicate that complement activation leading to generation of MAC may possibly be involved in the pathogenesis of vascular injury in a significantly large number of skin lesions and of HSP nephritis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Physics and chemistry of minerals 20 (1993), S. 86-90 
    ISSN: 1432-2021
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: Abstract Laser-heated experiments in a diamond anvil cell have been performed on high pressure melting of nickel up to 700 kbar. The laser heating system consists of diamond anvil cell, Nd:YAG and argon lasers, spectrograph with diode array, computer with software, CCD camera with monitor and optics. Experiments on melting of tungsten, nickel and platinum at 1 bar outside the diamond anvil cell and melting of nickel below 80 kbar in the cell were carried out to check the system for pressure and temperature measurements. The results show that for solid pressure medium the uncertainties in measurements of pressure at the experimental spot vary between ±5 kbar at 100 kbar and ±25 kbar at 660 kbar. Spectroradiometrically determined temperature is reliable within ±70 K. Melting was detected in situ by visual observation. The melting point of nickel at 660 kbar has been found to be 2557 ±66 K.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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