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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 1407-1412 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The excitation and radiative recombination mechanisms of carriers in electroluminescent porous silicon (PS) have been studied for the device with the structure of Au/PS/n-type Si. Experiments focus on the electroluminescence (EL) and photoluminescence (PL) spectra, the current-voltage-EL intensity relationship and its temperature dependence, and the excitation-wavelength dependence of the electric-field-induced PL quenching. The results of these experiments suggest the following points: (1) the EL occurs mainly near the Au/PS contact; (2) there exists an extremely high electric field at the Au/PS contact; (3) the EL originates from radiative recombination of strongly localized excitons; and (4) the radiative recombination rate is in proportion to the diode current. Based on these observations, an operation model is proposed. In our model, a large number of electrons and holes are generated in the PS layer by a field-assisted mechanism. Light emission occurs by radiative recombination of these electrons and holes via localized states. Because of field-enhanced carrier separation, however, the EL efficiency of this device is limited to a relatively low value of about 0.05%. Possible ways to improve the EL characteristics are discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1986-1988 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that the introduction of a porous structure into single-crystal Si produces substantial changes in the photoelectronic properties. The porous Si (PS) layer is formed by anodization of p-type Si wafers in a HF solution. The photoconduction cells used in this study consists of a semitransparent thin Au film, PS, Si substrate, and Al ohmic contact. The photoconductive behavior of PS is characterized by an extremely high dark resistivity, a definite photosensitivity for visible light, and an intrinsic bias voltage dependence of the spectral response. These properties, which are interpreted to be the result of a band-gap widening in PS, provide further support of the assumption that the visible luminescence of PS is explained by the band scheme.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4841-4844 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The operating peak energy of a porous silicon (PS) cavity can be completely controlled over a wide range of 1.5–2.2 eV, using a PS-based Fabry–Perot resonator composed of a light-emitting active PS layer and two high-reflectivity mirrors. When the PS devices are excited by a uv laser, quite narrow spectra (10–40 meV in full width at half-maximum) are observed without any significant signs of side mode. The central photon energy is precisely and continuously tuned simply by changing the anodization parameters. The key issues of the controlled device operation are adjustment of the optical thickness of the active PS layer to an appropriate value and fabrication of the quarter-wavelength multilayered PS mirror with a high reflectivity. The spectral qualities of the emitted light are also discussed by theoretical analyses on the basis of a simplified model. These results suggest that the PS devices operate as sharp band-pass optical filter and the PS materials are available for novel silicon-based microphotonics. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5274-5278 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A fabrication technology of three-dimensionally buried porous silicon (PS) optical waveguide with an extremely high refractive index contrast is presented, including its fundamental properties. The origins of attenuation losses are investigated by experimental and theoretical analyses in terms of microscopic observations, edge emission measurements, polarization mode determination of guided wave, and evaluation of bending loss. The results of these studies indicate that attenuation losses in PS waveguides are due to self-absorption by residual silicon, structural and optical inhomogeneities in the core region, and roughness at interfaces between the core and the cladding layers. Some possible ways for reducing these attenuation losses are discussed. It is also demonstrated that a buried bent PS waveguide with an extremely small curvature of 250 μm can be fabricated by simple planar processing, and that a visible optical wave propagates along it owing to a significantly high refractive index contrast between the core and the cladding layers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 4319-4324 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Highly efficient electroluminescence (EL) is obtained at low operating voltage (〈5 V) from n+-type silicon-electrochemically oxidized thin porous silicon–indium–tin–oxide junctions. Continuous wave external quantum efficiency greater than 1% and power efficiency of 0.37% have been achieved. Considerable reduction of leakage current accounts for the enhancement of EL efficiency upon oxidation. The EL time response ((approximate)30 μs) is slower than the photoluminescence one, due to slow electrical charging of porous silicon. No degradation of quantum efficiency is observed during operation and upon aging. This is attributed to the electrochemically grown oxide, which should provide a better surface passivation than the initial hydrogen coverage. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 5487-5488 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion-implantation studies of (CH)x films were carried out with ∼10-keV sodium ions. The temperature dependence of the sheet resistance of the implanted layer exhibited a thermal-activation-type behavior. Its activation energy decreased with increasing the ion dose. A long-term observation of the capacitance-voltage characteristics of an implanted p-n junction showed that a step junction was formed long after implantation as a result of the competition between defects annealing and dopants diffusion. These results ensure that low-energy ion implantation is a useful process for the n-type doping of (CH)x.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6365-6367 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method is proposed to control the wavelength of visible photoluminescence (PL) from porous silicon (PS). This is based on the post-anodization illumination technique which employs a filtered light with various maximum cutoff photon energies. As the illumination time increases, the PL spectra shift toward the higher energy side. This blue shift tends to stop at the time when the PL peak energy becomes close to the cutoff photon energy. The emission wavelength can be controllably tuned in a wide spectral range by changing the cutoff filter. These results give us a strong indication that the visible PL of PS is closely related to interband excitation in Si nanocrystallites, not to some surface chemical compounds.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 398-402 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoinduced proton injection properties of amorphous thin WO3 films have been studied for a cell of the form quartz glass/semitransparent Au/ethanol/WO3/indium-tin-oxide- coated glass. When the cell was illuminated with near-uv light through a quartz window under open circuit conditions, a definite reversible change was induced in the optical and electrical properties of WO3 films. On the basis of some experimental analyses, this effect is attributed to photointercalation (PI) of protons into WO3 films. It is also demonstrated that WO3-based PI cells efficiently operate as an erasable device for storage and modulation of optical information.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 354-358 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The output energy distribution of microchannel plates with different output electrode structures has been studied experimentally. It is shown that the penetration depth of the output electrode into the microchannel plates ω is a very important factor affecting both the output energy spread and the gain. When ω becomes twice the length of a channel diameter, the unfavorable tail component in the energy distribution can be suppressed. Improvement in the output energy spread, however, results in a considerable gain reduction. These characteristics are clarified by the internal current behavior in MCPs inferred from two operating dynode currents at the input and output ends.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1329-1331 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The output energy spread of a microchannel plate has been studied experimentally in a wide range of operating conditions. The energy distribution is found to consist of a sharp main peak with the full width at half-maximum of a few electron volts and a long tail extending over a wide energy range. These two components are presumably caused by two distinct regions of the potential distribution near the output end produced by the electrode penetrating into a certain depth within the microchannels. The tail component shows a significant change, particularly in the unsaturated operation mode. The resultant variation in the relative number of high-energy output electrons may have a detrimental effect on the spatial resolution of the image intensifier.
    Type of Medium: Electronic Resource
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