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  • American Institute of Physics (AIP)  (7)
  • Public Library of Science (PLoS)
  • 2015-2019
  • 1985-1989  (7)
  • 1988  (7)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1121-1125 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A new technique is described to study heterostructure field-effect transistors. This technique is based on the application of an electric field perpendicular to the channel via a p-doped substrate. The measurements demonstrate that the centroid of the two-dimensional electron gas resides approximately 10 nm below the heterointerface and that application of a negative substrate potential increases the confinement of these charges towards the interface. A negative substrate voltage decreases the K' factor of the transistor and also reduces the well capacity. Capacitance voltage measurements confirm that a parasitic channel in the donor layer can be formed and that it is shielded from the substrate by the two-dimensional electron gas.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 29 (1988), S. 305-307 
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: Nonstationary solutions of linear Fokker–Planck equations with arbitrary drift and diffusion coefficients are derived. Using Lie algebraic techniques the time-evolution operator is given as a product of exponentials of the differential operators appearing in the equations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3380-3392 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Experiments have characterized the operation of a LaB6 triode gun in a standard three-lens column of the type used for Gaussian electron-beam lithography and scanning electron microscopy. A series of images representing cross sections of the three-dimensional spatial distribution of current emitted from the gun is obtained by configuring the electron optics as a scanning confocal microscope. The gun acts as an immersion objective whose image is scanned by deflection coils and focused by the condenser lenses onto a pinhole transmission detector. Characteristics of the emission distribution include an emission image of the cathode surface situated between two distinct beam crossovers whose origin is either the apex (001) and {310} planes or the large {110} planes on the machined 90° cone angle of the cathode surface. Virtual objects are imaged when the back focal plane of the condensers falls inside the high-field region of the gun. The target axial brightness is dependent on gun excitation and angular acceptance angle. The temperature-dependent brightness of the cathode is used to determine its effective emission area, work function, and surface electric field. Beam positional stability of three-carbon-mounted LaB6 directly heated cathodes is measured. However, for measurement times ≤100 h the drift rate is found to be limited by thermal expansion of the movable anode assembly and not the particular cathode mounting technique.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1098-1100 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report electrical transport and optical studies of the efficiency with which an In0.2Ga0.8As/GaAs strained-layer superlattice (SLS) can filter threading dislocations generated in a thick In0.1 Ga0.9 As layer grown on GaAs. The electrical studies, the first of their kind, rely on a novel test structure which allows electrical characterization of just the top portion of the SLS, with the bottom portion acting as the dislocation filter. For optical characterization we detect dislocations directly by photoluminescence microscopy. The electrical results show that ∼3–6 periods of filtering are needed to attain high mobilities. The photoluminescence microimages show a small density of dislocations near the top of an eight-period SLS but no dislocations for 11 or more periods. Filtering with In0.2Ga0.8As/GaAs SLS's is more effective than with GaAs0.8P0.2/GaAs SLS's, possibly because of larger interlayer differences in strain and elastic constants for the former.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 377-379 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The critical layer thickness for InxGa1−xAs layers in InxGa1−xAs/GaAs single strained quantum wells (SSQW's) and strained-layer superlattices (SLS's) are investigated. Photoluminescence microscopy (PLM) images and x-ray rocking curves for two series of SSQW and SLS structures corresponding to many different layer thicknesses were obtained. We find that the PLM technique, which directly images dislocations and is sensitive to low dislocation densities, is much more suitable for determining the onset of dislocation creation. The x-ray technique can detect lattice relaxation by dislocations but only at relatively high densities of dislocations. Using the former technique, we determine critical thicknesses of 190 A(ring) for SSQW's and 250 A(ring) for SLS's with x≈0.2. These results are near the theoretical predictions of J. W. Matthews, S. Mader, and T. B. Light [J. Appl. Phys. 41, 3800 (1970)] (150 and 300 A(ring), respectively) and are much lower than results obtained by x-ray or other techniques which sense lattice relaxation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1961-1963 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Both large photoconductive gain and long wavelength photoresponse were observed in lateral photodetectors constructed from type II, InAsSb, strained-layer superlattices. In a novel, four-layer superlattice, gain values as large as 90 are reported with a long wavelength cutoff of 8.7 μm at 77 K. The gain is sensitive to the structure and composition of the superlattice, and the sweepout of minority carriers is eliminated with the appropriate contacts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: GaAs/In0.2 Ga0.8 As structures with two paralleled 10 nm quantum wells, modulation doped from the top, bottom, and middle with Be, have been fabricated into multiple strained quantum well field-effect transistors (MQWFET's) with 1×150 μm2 Ti/Au gates and examined both illuminated and in the dark at 300 and 77 K. Measurements on van der Pauw structures fabricated simultaneously with the transistors showed hole mobilities and sheet carrier densities to be 200, 3100, and 8040 cm2/V s, and 5.7×1012, 1.8×1012, and 1.5×1012 cm−2 , at 300, 77, and 4 K, respectively. Shubnikov–de Haas measurements made below 4 K verified the existence of a double-channel two-dimensional hole gas with a strain-shifted light-hole ground state in the quantum wells with an effective hole mass of 0.15 me . A representative p-channel MQWFET showed well-saturated common-source output characteristics, both illuminated and unilluminated, at all measurement temperatures. Measured peak extrinsic transconductances and peak saturated drain currents for the unilluminated 1 μm device were 31 and 60 mS/mm and 27 and 67 mA/mm, at 300 and 77 K, respectively.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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