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  • Articles: DFG German National Licenses  (516)
  • Electronic Resource  (516)
  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4401-4406 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate how the mobility and carrier density of AlGaAs/GaAs two-dimensional electron gas are influenced by the fabrication process with plasma-excited chemical vapor deposition (plasma-CVD) SiN film. These properties are greatly reduced by annealing with plasma-CVD SiN film as a cap but are restored by reannealing after removing the SiN film. We further use capacitance-voltage measurements to investigate the influence of this same process on a more simplified structure, Si-doped GaAs layer. Annealing with a plasma-CVD SiN film changes the defect density of Si-doped GaAs in two, temperature dependent ways: annealing below 380 °C reduces deposition damage, and annealing above 300 °C produces new defects, which might be caused by the film stress. These new defects can be reduced by reannealing after removing the SiN film. © 1995 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 76 (1994), S. 2330-2335 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Buried wires with lateral potential barriers provided by AlGaAs/GaAs heterointerfaces have been fabricated by wet etching and metalorganic chemical vapor deposition regrowth. Burying the wire was proven to enhance the electrical transport properties; for example, it decreased the critical width and increased the subband energy separation. Two-dimensional simulation using the Poisson equation was performed to obtain the potential profile of both as-etched and buried wires. The quantum energy levels corresponding to the lateral confinement were calculated for the obtained potential profiles. The calculated energy separations agreed well with the experimental ones and the subband energy separation of the buried wire was larger than that of the as-etched wire for the same effective width. These results show that burying wire is effective for creating strong lateral confinement.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4119-4121 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-temperature operation of InAsP-based laser diodes at 1.3 μm has been realized according to guidelines of a large conduction-band-offset material (ΔEc) with a large optical confinement factor (Γ). Using photoluminescence excitation spectroscopy measurements, it was found that the conduction-band offset of InAs0.52P0.48P/InGaAsP is the half of the band-gap energy difference (0.5 ΔEg), which is larger than that of conventional quaternary material systems. A strain-compensation growth technique enabled the fabrication of a large number of wells for large Γ. For broad-area laser diodes, the maximum operating temperature increased as the number of wells increased from 4 to 15. In buried heterostructure lasers with ten wells, with high-reflectivity coating on both facets, continuous-wave lasing operation at temperatures up to 150 °C was achieved with a characteristic temperature of 59 K (30〈T〈70 °C) demonstrating the suitability of InAsP for high-temperature operation. © 1995 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 75 (1994), S. 5904-5906 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polyphase eddy current testing is proposed. The operating principle of this system is as follows. The polyphase eddy current testing system may be regarded as one of the polyphase transformers. Primary balanced polyphase coils are star connected and secondary polyphase circuits are composed of the target. When balanced polyphase currents are fed into the primary coils, zero phase voltage is detected if the target has defects. No zero phase voltage is detected if the target has no defects. It is found that this method has a higher sensitivity compared with that of conventional eddy current testing.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 1135-1142 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The reorientation behavior of nematic liquid crystal molecules induced by an electric pulsed field was investigated by means of time-resolved optical waveguide spectroscopy (TROWS) which was developed to observe transient changes in dielectric constants and to measure the thickness of a thin dielectric medium. Time evolution of the waveguide mode patterns was successfully obtained by using TROWS, which records the reflectivity as both functions of the incident angle of laser light and the time from switching-on or -off of the external electric field. The transient dielectric tensor profile in the 4′-pentyl-4-cyanobiphenyl (5CB) layer both after switching-on and -off of the electric field could be precisely determined in a three-dimensional coordinate system by using Deuling's theory which treats the orientational deformation induced by an external electric field. Theoretical analysis of TROWS data clearly indicated that half of the 5CB molecules rotate clockwise in the plane defined by the rubbing direction and the substrate normal, and the other half rotates counter-clockwise in the same plane. The counter rotation compensates the effect of birefringence observed in the direction parallel and perpendicular to the rubbing direction and the reorientation kinetics could be well described by the Ericksen–Leslie equation. Relaxation behavior from homeotropic to planar orientation could be treated as an orientation diffusion process by applying a Gaussian distribution function to the maximum tilting angle at the middle of the cell. We report the usefulness of TROWS which provided more detailed information about the dynamics of the 5CB molecules. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1378-1380 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Properties of the silicon surface cleaned by the irradiation of the hydrogen electron cyclotron resonance plasma has been studied by x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and Fourier transform infrared spectroscopy. It was confirmed that the irradiation of the hydrogen plasma eliminated both a native oxide layer and a contaminated carbon layer from the silicon surface. In addition, it was found that the surface has the retardation effect on the air oxidation at room temperature. However, the plasma irradiation caused the minute roughness on the surface and hydrogen penetration into the bulk.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1245-1247 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gallium phosphide films are successfully grown on (100) Si substrates by a new hydride vapor phase epitaxy. Mixing of reactant vapors just above the substrate makes the growth rate as high as 50 nm/min even in the temperature range of 350–450 °C. This makes the two-step growth procedure applicable for growing a single domain GaP film on Si from H2-HCl-PH3-Ga reactants. An etch pit density of 7.5×106 cm−2 and a full width at half-maximum of 93 arcsec in a double-crystal x-ray rocking curve are achieved. Green light-emitting diodes with 565 nm peak wavelength are successfully fabricated using nitrogen-doped GaP films grown on Si.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1664-1669 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Effects of ion irradiation on oxidation of silicon at a temperature as low as 130 °C in an argon and oxygen mixed plasma excited by electron cyclotron resonance interaction have been investigated. The growth rate of the oxide films increases with increasing incident energy and flux of argon ions, and the thickness increases proportionally to the root square of the oxidation time, which suggests that the growth rate is limited by diffusion of oxidants enhanced by irradiation with argon ions. Effects of substrate bias on the oxidation characteristics have been also investigated. The growth rate increases with increasing positive bias, and the growth kinetics deviate from diffusion limited with increasing thickness. The bias dependence of the growth rate is caused by drift of negative oxidants enhanced by the electric field established in the oxide films. Moreover, it is shown that the electrical properties of the oxide films are improved by applying positive substrate bias. The improvement is due to a reduction of irradiation-damage in the initial oxidation stage. On the basis of the experimental results, it is concluded that the reduction of the incident energy and the flux of argon ions in the initial oxidation stage is essential to improve electrical properties of the oxide films. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1050-1054 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the absolute density and the spatial distribution of silicon atoms in a SiH4-He-Ar dc glow discharge measured by the laser-induced fluorescence method. The absolute sensitivity of the fluorescence-photon-counting system was calibrated by using the same system to measure Rayleigh scattering by Ar gas in the discharge chamber. The fluorescence quantum efficiency and the polarization degree of emitted light were measured to confirm the absence of excited-state quenching induced by collisions with the buffer-gas atoms. The measured spatial distribution profile of the ground-state silicon atoms is compared with that of the excited-state atoms.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    USA/Oxford, UK : Blackwell Science Ltd
    Cephalalgia 16 (1996), S. 0 
    ISSN: 1468-2982
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A case of primary low cerebrospinal fluid (CSF) pressure syndrome with galactorrhea is reported. Magnetic resonance imaging demonstrated diffusely enhanced meninges, edematous brain, and enlarged pituitary gland. Coincidental enlargement of pituitary gland and edematous brain due to low CSF pressure compressed the pituitary portal system. The 1ow-perfused anterior lobe of pituitary gland would be the mechanism of galactorrhea.
    Type of Medium: Electronic Resource
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