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  • 1
    Electronic Resource
    Electronic Resource
    Annealing effects on structures and optical properties of silicon nanostructured films prepared by pulsed-laser ablation in inert background gas (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5075-5080 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied the annealing effects on the structures and optical properties of silicon (Si) nanostructured films. The Si nanostructured films were synthesized by pulsed-laser ablation in inert background gas. It was found that the Si nanostructured films partially include an amorphous-like structure under the as-deposited condition. After annealing in nitrogen gas, the crystallinities of the Si nanoparticles recovered, and four visible photoluminescence (PL) bands (1.7, 2.2, 2.7, and 3.1 eV) appeared at room temperature. Furthermore, upon subsequent annealing in oxygen gas, strong quantum confinement effects for both phonons and carriers of the Si nanoparticles appeared, and the relative intensity of the 2.7 eV blue band increased. We fabricated electroluminescent (EL) diodes with active layers of annealed Si nanostructured films, and verified visible EL spectra at room temperature, which exhibited the same trends as the PL spectra. A possible explanation for the increase of relative intensity of the 2.7 eV blue band is the increase of the amount of silicon dioxide, which contains neutral oxygen vacancy defects, in the Si nanostructured films. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1412834
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  • 2
    Electronic Resource
    Electronic Resource
    Ecology Mechanisms for consumer diversity (2006)
    [s.l.] : Nature Publishing Group
    Nature 439.2006, 7072, E1-, (2 S.) 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Arising from: W. A. Nelson, E. McCauley & F. J. Wrona Nature 433, 413–417 (2005); Nelson et al. reply. A variety of mechanisms can theoretically produce competitive coexistence in nature, making it hard to identify a ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature04526
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid evolution drives ecological dynamics in a predator–prey system (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 424 (2003), S. 303-306 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Ecological and evolutionary dynamics can occur on similar timescales. However, theoretical predictions of how rapid evolution can affect ecological dynamics are inconclusive and often depend on untested model assumptions. Here we report that rapid prey evolution in response to oscillating ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01767
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  • 4
    Electronic Resource
    Electronic Resource
    Stay cool: habitat selection of a cyclopoid copepod in a north temperate oligotrophic lake (2003)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 48 (2003), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. We studied the vertical distributions of Cyclops cf. sibiricus in Lake Toya, a north temperate oligotrophic lake. During the winter circulation period, their distribution was vertically homogeneous both day and night. During the summer stratification period, C. cf. sibiricus stayed below the thermocline. Diel vertical migration (DVM) was pronounced in advanced developmental stages, although the upper limit of the migration became deeper as the thermocline gradually descended. This seasonal change was observed throughout the 4-year study period, implying that thermal structure is the primary determinant of C. cf. sibiricus distribution.2. In a field experiment, C. cf. sibiricus incubated in the summer epilimnion, which most of the population never experience, developed faster and grew better than in their original habitat. We consider that trans-thermocline DVM would not have evolved because of possible disadvantages such as the cost of migration offset the benefit observed in the field experiment. The rapid temperature change at the thermocline may act as a swimming-cost estimator for the copepod.3. Low food availability in deep water during the summer stratification period seemed to determine the lower limit of C. cf. sibiricus distribution, and the copepod minimised the risks of predation by fish via DVM. These results suggest that C. cf. sibiricus modified their distribution seasonally to obtain maximum benefit in terms of individual fitness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2003.01108.x
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  • 5
    Electronic Resource
    Electronic Resource
    Time-dependent p-n junction characteristics underneath TiN/Ti contact metal (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5272-5277 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-dependent p-n junction characteristics (junction depth: xj∼0.2 μm) underneath TiN/Ti contact metal have been determined in terms of contact interface crystallinity. Reverse bias (≥6.0 V) soft-breakdown characteristics result in a leakage current increase during reverse bias and temperature aging stress. It has been elucidated that this degradation is dependent on the crystallinity of Ti-Si interdiffused layers at the contact interface and the p-n junction polarity. The degradation is observed only in amorphous Ti-Si contacted n+-p junctions. Nevertheless, in amorphous Ti-Si contacted p+-n junctions and crystalline TiSi2 contacted n+-p and p+-n junctions, the degradation does not appear. In the case of the amorphous Ti-Si contacted n+-p junction, it is concluded that the time-dependent degradation is caused by diffusion of positively ionized Ti enhanced by the applied electric field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357177
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  • 6
    Electronic Resource
    Electronic Resource
    Interface microstructure of titanium thin-film/silicon single-crystal substrate correlated with electrical barrier heights (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 827-832 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The titanium (Ti)/single-crystal silicon (Si) interface has been examined by cross-section high-resolution transmission electron microscopy (HRTEM) combined for the first time with 2-nm-diam probe, energy-dispersive spectrometry. HRTEM shows that thin Ti-Si alloy formation always occurs at the interfaces, even in the as-deposited state. The thickness of the reacted alloy depends on the crystallinity of the Si surface, but does not depend on impurities or doping level. Crystallization of the Ti-Si alloy depends on the annealing temperature; it remains in the amorphous phase after annealing at temperatures lower than 430 °C, and the C49 TiSi2 crystal phase was observed as the first crystalline phase after annealing at 460–625 °C. The composition of the Ti-Si alloy at the Si interface is close to TiSi2, and it remains amorphous with variable composition across the alloy. It seems that the electrical barrier height is determined by the degree of crystallinity of TiSi2 at the Si interface. The barrier height for TiSi2/p-type Si interface decreases from 0.73 to 0.57 eV, accompanied by the crystallization of TiSi2 at around 460 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349641
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  • 7
    Electronic Resource
    Electronic Resource
    Structure and electrical properties of interfaces between silicon films and n+ silicon crystals (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 668-671 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the morphology and electrical characteristics of the interfaces between silicon-implanted, low-pressure chemical-vapor-deposited (LPCVD) silicon films with an n+ single-crystal silicon substrate. Using high-resolution transmission electron microscopy, it is shown that the silicon implant causes a "balling up'' of the native oxide layer at the interface and epitaxial growth occurs in the LPCVD silicon film even after rapid thermal annealing at only 940 °C for 30 s. This morphological change results in a realization of a low-ohmic-resistivity LPCVD silicon/ n+ single-crystal silicon contact even at a sub-half-μm size, although the unimplanted contact becomes nonohmic. The leakage current for the implanted contact is as low as that for the unimplanted one in shallow junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343101
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  • 8
    Electronic Resource
    Electronic Resource
    Monodispersed, nonagglomerated silicon nanocrystallites (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2043-2045 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate the synthesis of monodispersed, nonagglomerated silicon (Si) nanocrystallites, using an integrated process system composed of a unit for the formation of nanocrystallites by pulsed-laser ablation in an inert background gas, a unit for classification using a differential mobility analyzer (DMA), and a unit for deposition onto a substrate using a nozzle jet. The DMA has been designed to operate under pressures less than 5.0 Torr. We have synthesized nonagglomerated Si nanocrystallites of 3.8 nm mean diameter and 1.2 geometrical standard deviation on carbon thin films using this integrated process system. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1360236
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  • 9
    Electronic Resource
    Electronic Resource
    Structures and optical properties of silicon nanocrystallites prepared by pulsed-laser ablation in inert background gas (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1389-1391 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon (Si) nanocrystallites have been synthesized using pulsed-laser ablation in inert background gases, for studying the structures and optical properties as one of the quantum confinement effects. We extracted a process condition where well-dispersed Si nanocrystallites devoid of droplets and debris are prepared, by varying excitation laser conditions. Furthermore, we investigate the influence of the inert background gas pressures on transition from amorphous-like thin films to nanocrystallites. It was clarified that there is a processing window of the inert background gas pressure in which the quantum confinement effects for carriers and phonons become apparent. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126041
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  • 10
    Electronic Resource
    Electronic Resource
    Electroluminescence of silicon nanocrystallites prepared by pulsed laser ablation in reduced pressure inert gas (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5427-5432 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on an electroluminescent (EL) diode with novel active layers of silicon (Si) nanocrystallites. The Si nanocrystallite active layer was prepared by pulsed laser ablation in an ambient of reduced pressure inert gas. The structure of the EL diodes was semitransparent platinum (Pt) electrode/Si nanocrystallite layer/p-type Si/Pt electrode. We have observed visible spectra of not only photoluminescence around 2.07 eV, but also EL around 1.66 eV at room temperature. The EL diodes showed a rectifying behavior caused by a Schottky-like junction. Furthermore, we have found that the EL diodes showed strong nonlinear dependence of EL intensity on current density. A possible mechanism of the EL diode emission is impact ionization by minority hot carriers injected through the surface oxide layers and the successive radiative recombination. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367373
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