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  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1765-1767 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room temperature photoreflectance (PR) was used to investigate the surface state densities of GaAs and In0.52Al0.48As surface intrinsic-n+ structures. The built-in electric field and thus the surface barrier height are evaluated using the observed Franz–Keldysh oscillations in the PR spectra. Based on the thermionic emission theory and current-transport theory, the surface state density as well as the pinning position of the Fermi level can be determined from the dependence of the surface barrier height on the pump beam intensity. Even though this method is significantly simpler, easier to perform, and time efficient compared with other approaches, the results obtained agree with the literature. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 920-926 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A lattice-matched In0.53Ga0.47As/In0.52Al0.48As single quantum well (SQW) structure grown by gas source molecular beam epitaxy has been investigated by photoreflectance (PR) and photoluminescence (PL). The PR measurements allowed the observation of interband transitions from the heavy- and light-hole valence subbands to the conduction subbands. The transition energies measured from the PR spectra agree with those calculated theoretically. Two features corresponding to the ground state transition coming from the SQW and the band gap transition generated from the buffer layer are observed in the PL spectra and are in good agreement with the PR data. The effect of the temperature on the transition energies is essentially same as that in the gap transition of the bulk structure. The values of the Varshni coefficients of InGaAs/InAlAs were obtained from the relation between the exciton transition energy and the temperature. The built-in electric field could be determined and located from a series of PR spectra by sequential etching processes. The phase spectra obtained from the PR spectra by the Kramers–Kronig transformation were analyzed in terms of the two-ray model, and calculated the etching depth in each etching, and thus leading to the etching rate. The etching rate obtained from phase shift analysis agrees with that measured by atomic force microscopy. The etching results suggest that a built-in electric field exists at the buffer/substrate interface and it also enables us to determine the etching rate. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1296-1298 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Phase images of 20–30-nm-diam silicon spheres were collected by holographic methods in a field-emission transmission electron microscope. The spherical geometry enables the effect of specimen thickness on the electron-wave phase to be separated from the intrinsic Si electron-optical refractive effects allowing a determination of the mean inner potential Φ0. This work finds Φ0=11.9±0.9 V characterizing amorphous Si and 12.1±1.3 V characterizing crystalline Si. The phase images can resolve a 2-nm-thick native oxide layer and give Φ0 for SiO2=10.1±0.6 V. The phase data can quickly recognize a surface layer, and the effect of a surface layer on the determination of the bulk mean potential can be minimized. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 2857-2859 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Built-in electric fields and interfacial state densities (Dit) in a series of oxide–GaAs heterostructures fabricated by in situ molecular beam epitaxy were studied using room temperature photoreflectance. The samples investigated were air-, Al2O3–Ga2Ox–, and Ga2O3(Gd2O3)–GaAs. We found that the built-in electric fields are 48, 44, and 38 kV/cm for air-, Al2O3-, and Ga2Ox–GaAs samples, respectively. For the Ga2O3(Gd2O3)–GaAs sample, the built-in electric field is negligibly small, indicating a very low interfacial state density. Estimated by the low field limit criterion, Dit is less than 1×1011 cm−2 eV−1. Our results on the Ga2O3(Gd2O3)–GaAs sample are consistent with the data obtained previously using capacitance–voltage measurements in quasistatic/high frequency modes and photoluminescence measurements. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3452-3454 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoreflectance measurements have been performed on a δ-doped GaAs homojunction. Two Franz–Keldysh oscillation features originating from two different regions (a buffer layer and a top layer) of the structure superimpose with each other in the photoreflectance spectrum. By properly selecting the reference phase, one of the features can be suppressed, thus enabling us to determine the electric fields from the two regions unambiguously. The electric field in the top layer is 3.5±0.2×105 V/cm, which is in good agreement with theoretical calculation. The electric field in the buffer layer is 1.2±0.1×104 V/cm. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of texture studies 29 (1998), S. 0 
    ISSN: 1745-4603
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A device to objectively measure the melt/flow behavior of cheeses at different temperatures was built consisting of a temperature-controlled heater, an LVDT (linear variable differential transformer), and a personal computer with a data acquisition system. This device, named UW Meltmeter, operates in the lubricated squeeze-flow configuration and can be used either alone at a constant force or in conjunction with a universal testing machine at a constant deformation rate. A marker technique was used to verify the shear-free squeezing flow assumption. The flow of Mozzarella cheeses with 14 and 43% fat content was studied at 40 and 60C under constant force (0.7 and 0.9 N) and constant cross-head speed (0.5 and 2.5 cm/min). Biaxial extensional strain rate and biaxial stress growth coefficient were calculated. The results supported the expected trend of increased meltability at higher fat levels and at higher temperatures.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Psychiatric Research 10 (1974), S. 319 
    ISSN: 0022-3956
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Optics Communications 48 (1984), S. 398-402 
    ISSN: 0030-4018
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Chromatography A 628 (1993), S. 133-137 
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Solid State Electronics 21 (1978), S. 609-615 
    ISSN: 0038-1101
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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