GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1027-1031 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed time-varying photoconductivity and persistent photoconductivity in porous silicon, both with time-evolution scales of the order of several minutes or hours. The time evolutions depend on the wavelength and the intensity of the illuminating light. The data indicate the presence of at least two competing mechanisms, one is tentatively related to photoinduced creation of charge carriers in the silicon substrate followed by diffusion into the porous silicon layer, and the other is tentatively related to desorption of hydrogen from the porous silicon. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 6189-6192 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An easy and very reproducible method to produce porous silicon by light-stimulated etching of crystalline silicon in HF is described, and the formation mechanism is discussed in terms of carrier diffusion and band bending near the surface. The method avoids the use of electrodes and electrochemical etching. The photosynthesized porous silicon shows bright photoluminescence. Spectra recorded at room temperature for n-type as well as p-type silicon are presented. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 6978-6985 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have undertaken a systematic study of porous silicon with the use of photoconductivity and photoluminescence. During this, we have observed at least three kinds of time-varying photoconductivity, of which two reduce the conductivity and one increases the conductivity during illumination. In addition, we have observed persistent photoconductivity. The time developments of the photoconductivity as well as the persistent photoconductivity depend in intricate ways on parameters such as the wavelength and intensity of the illuminating light, the potential drop across the sample, the surface treatment, and the dark current value. The time scale of these time-varying effects ranges from a few minutes to several hours. The results are discussed in terms of the photoelectric properties of the supporting silicon wafer, diffusion of hydrogen, and photoinduced desorption of hydrogen. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 4 (1997), S. 147-154 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The large penetration power of high-energy X-rays (〉60 keV) raises interesting prospects for new types of structural characterizations of polycrystalline materials. It becomes possible in a non-destructive manner to perform local studies, within the bulk of the material, of the fundamental materials physics properties: grain orientations, strain, dislocation densities etc. In favourable cases these properties may be mapped in three dimensions with a spatial resolution that matches the dimensions of the individual grains. Imbedded volumes and interfaces become accessible. Moreover, the high energies allow better in-situ studies of samples in complicated environments (industrial process optimization). General techniques for research in this energy range have been developed using broad-band angle-dispersive methods, on-line two-dimensional detectors and conical slits. Characterizations have been made at the level of the individual grains and grain boundaries as well as on ensembles of grains. The spatial resolution is presently of the order of 10–100 μm. Four examples of applications are presented along with an outlook.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1572-9605
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Superstructure reflections at low temperatures in La1−x Sr x MnO3 single crystals indicating charge order in samples containing 12.5% and 15% of Sr have been observed. The positions of the reflections in reciprocal space suggest a fourfold unit cell referring to the cubic perovskite structure. The onset temperatures for charge ordering are 150 K and 180 K for x=0.125 and x=0.15, respectively. Especially in the sample with the lower Sr concentration, the onset is correlated to a jump in resistivity measured on the same sample.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 117 (1999), S. 455-459 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hard x-ray diffraction experiments at the wiggler beamline BW5 at the synchrotron radiation laboratory HASYLAB in Hamburg have been very suc-cesful in studying the charge stripe ordering of holes in the CuO2 plane of La1.48Nd0.4Sr0.12CuO4. This compound has been previously studied with neutron diffraction, leading to the idea of charged stripes as antiphase domain boundaries for antiferromagnetic ordering of the Cu spins. In our x-ray experiments we have shown that correlation between the stripes exists also perpendicular to the CuO2 planes. The modulation of the intensities along the l-direction have been measured at several positions in reciprocal space. We have been succesful in observing stripe peaks also in samples with Sr doping levels of x = 0.15 and x = 0.10, whereas no stripe signal has been observed in a sample with x = 0.20.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1434-6036
    Keywords: PACS. 61.10.Nz Single-crystal and powder diffraction - 71.38.+i Polarons and electron-phonon interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Superstructure reflections due to charge ordering have been observed in single crystals using X-ray diffraction. The critical temperatures for the ordering process are 150 K and 180 K in samples with Sr concentrations of and , respectively. For x =0.125 the charge order transition correlates with a drastic resistivity enhancement, while a much smaller change of the resistivity is found for x = 0.15. It is argued that the onset of charge ordering in the sample with x = 0.125 is related to the suppression of co-operative Jahn-Teller distortions which is initiated by rising ferromagnetism.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 12 (1999), S. 509-513 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Superstructure reflections due to the ordering of holes into stripes in have been studied with high energy X-ray diffraction. These reflections have been observed clearly for the first time in a sample which is superconducting at low temperatures ( K). The stripe peaks vanish above 62(5) K whereas the magnetic signal of the stripe ordering which has been seen with neutrons before is already suppressed at K. Our results confirm that the ordering of spins and holes is driven by the charges as it is found in the case of La1.6-xNd0.4SrxCuO4 at the doping level of x =0.12.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...