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  • 1
    Electronic Resource
    Electronic Resource
    Fulminant ulcerative colitis and parturition: a need to alter current management? (1994)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 101 (1994), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1994.tb13088.x
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  • 2
    Electronic Resource
    Electronic Resource
    Porous silicon photoluminescence: Implications from in situ studies (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 7009-7017 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence and Raman measurements have been performed on an anodized silicon surface in an HF/ethanol anodization solution and after replacement of this solution with water. Immediately after anodization and while resident in HF/ethanol, the porous silicon produced does not exhibit intense photoluminescence. Intense photoluminescence develops spontaneously in HF/ethanol after 18–24 h or with replacement of the HF/ethanol with water. The results are consistent with a quantum confinement mechanism in which electron-hole pair migration to traps and nonradiative recombination dominates the de-excitation pathways until silicon nanocrystals are physically separated and energetically decoupled by hydrofluoric acid etching or surface oxidation. Raman spectra show the development of nanometer-size silicon crystals concurrent with intense photoluminescence. Illumination of the silicon surface during anodization tends to inhibit the formation of nanocrystalline silicon, but even very thin layers (tens of nanometers or less) exhibit photoluminescence. As produced by anodization, the porous silicon surface is apparently inhomogeneous on the millimeter scale, showing large variations in photoluminescence intensity and peak wavelength. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363813
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  • 3
    Electronic Resource
    Electronic Resource
    The atomic scale structure and the electronic properties of a graded composition semiconductor layer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1603-1607 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the results of a study on the relationship between the structural and electronic properties of a graded layer of undoped AlxGa1−xAs, where x was specified to increase linearly from 0 to 0.2 over 50 nm. The layer was grown by molecular-beam epitaxy between layers of doped GaAs. A high-resolution dark-field transmission electron microscopy imaging technique of combining information from 002 and 002¯ reflections of AlxGa1−xAs allowed us to image the graded region with near atomic resolution. Differences between the predicted and measured diode performance of the graded layer are discussed in the light of our results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339946
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  • 4
    Electronic Resource
    Electronic Resource
    Hot-electron transport in In0.53Ga0.47As (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1842-1849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Monte Carlo routine has been used to simulate hot-electron transport across narrow regions of heavily doped In0.53Ga0.47As. The doping level/widths considered correspond to those proposed for the base of hot-electron transistors. For doping levels of order 1018 cm−3, the injected hot electrons suffer inelastic scattering by the coupled plasmon-optic phonon mode. The performance of hot-electron transistors is characterized by the base transfer factor which relates a change in collector current with a change in emitter current. The base transfer factor is determined from the simulations for a range of base widths and operating conditions. Results for InGaAs are compared with those for GaAs. Under comparable operating conditions, the InGaAs hot-electron transistor offers a higher transport efficiency and hence, higher current gain compared with that of GaAs. We have used the Monte Carlo routine to simulate the performance of experimental results from InGaAs hot-electron transistors. The simulations are in good agreement with the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339567
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  • 5
    Electronic Resource
    Electronic Resource
    Physics and design of hot-electron spectrometers and transistors (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3076-3079 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We explain how Monte-Carlo simulations may be used to calculate the transfer characteristics of GaAs hot-electron transistors, from which hot-electron spectra may be derived. We present such spectra for a range of doping densities and injection energies for a base width of 500 A(ring). We compare our results with those derived from other theories and suggest an experiment which should indicate their relative validity. Optimum parameters for base width and doping for high-frequency hot-electron transistors are derived and compared with available experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342702
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  • 6
    Electronic Resource
    Electronic Resource
    Selective porous silicon formation in buried p+ layers (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4182-4186 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a systematic microstructural study of enhanced lateral porous silicon formation in the buried p+ layers of n/p+/p− and p−/p+/p− structures. We find, surprisingly, extremely selective porous silicon formation due to the thin p+ layer in both structures, despite the absence of a p-n junction in the p−/p+/p− structure. The interface between the isolated island and the buried porous silicon layer was always located at the depth where the net p-type dopant concentration was 1–8×1015/cm3. The observed microstructure can largely be understood in terms of a recent model for porous Si formation in uniformly doped Si, proposed by Beale et al. [J. Cryst. Growth 73, 622 (1985)]. However, we also observe, for the first time, important effects unique to a nonuniform dopant concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339086
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  • 7
    Electronic Resource
    Electronic Resource
    Elementary reaction schemes for physical and chemical vapor deposition of transition metal oxides on silicon for high-k gate dielectric applications (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 6173-6180 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This article describes the kinetics of reactions that result in substrate consumption during formation of ultrathin transition metal oxides on silicon. Yttrium silicate films (∼40 Å) with an equivalent silicon dioxide thickness of ∼11 Å are demonstrated by physical vapor deposition (PVD) routes. Interface reactions that occur during deposition and during postdeposition treatment are observed and compared for PVD and chemical vapor deposition (CVD) yttrium oxides and CVD aluminum-oxide systems. Silicon diffusion, metal-silicon bond formation, and reactions involving hydroxides are proposed as critical processes in interface layer formation. For PVD of yttrium silicate, oxidation is thermally activated with an effective barrier of 0.3 eV, consistent with the oxidation of silicide being the rate-limited step. For CVD aluminum oxide, interface oxidation is consistent with a process limited by silicon diffusion into the deposited oxide layer. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1468253
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  • 8
    Electronic Resource
    Electronic Resource
    Porous silicon oxynitrides formed by ammonia heat treatment (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3842-3847 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Porous silicon and its oxide can be converted into porous silicon oxynitrides by ammonia heat treatment. For example, ammonia treatment at 1000 °C for 1 h following 850 °C, 30-min steam oxidation of porous silicon can result in up to 40 at. % nitrogen in the porous oxynitrides. These porous silicon oxynitrides are compositionally more uniform than ammonia-nitrided thermal oxides which exhibit nitrogen buildup at the oxide layer interfaces. However, the order of the oxidation and nitridation treatment matters: nitrided oxidized porous silicon exhibits higher electrical breakdown strength than nitrided porous silicon or oxidized nitrided porous silicon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346077
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  • 9
    Electronic Resource
    Electronic Resource
    Hot-electron transport in GaAs in the presence of a magnetic field (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1425-1427 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the results of the incorporation of magnetic field effects into the Monte Carlo simulation of hot electrons traversing narrow regions of heavily doped GaAs. In addition to accounting for the experimentally observed suppression of the ballistic contribution to the hot-electron spectrum, a further analysis allows us to infer the spread in transverse energy of the injected hot electrons.We attribute this loss of collimation to scattering by unscreened ionized impurities in the depletion region which is set up when a hot-electron injector is forward biased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98645
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  • 10
    Electronic Resource
    Electronic Resource
    Consequence of layer thickness fluctuations on superlattice miniband structures (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2641-2643 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The miniband structure of a perfect superlattice depends on the thicknesses and compositions of the constituent layers. We describe simple modeling of the consequences of fluctuations in the layer thickness. Experimental results from an asymmetric superlattice tunnel diode, where the presence of negative differential conductance reflects the existence of a miniband gap, are used to show how the sensitivity of the miniband structure to such fluctuations depends on the choice of layer thicknesses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100181
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