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  • 1990-1994  (4)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 5275-5276 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the thermal decomposition of native oxide on Si(100) under ultrahigh vacuum using high-resolution x-ray photoelectron spectroscopy (XPS). The native oxide was formed by wet chemical treatment (HCl/H2O2/H2O), a widely employed procedure for preparing atomically clean surfaces. XPS measurements revealed that high temperature heating ((approximately-greater-than)700 °C) leads to a remarkable alteration in Si 2p and O 1s spectra. After heating to 700 °C, the Si3+ structure increases and the O 1s full-width-at-half-maximum decreases. After heating to 800 °C, the Si4+ and O 1s intensity decreases but the Si2+ intensity remains almost unchanged. We suggest that the formation of volatile SiO is related to the Si3+ structure produced by high temperature annealing.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 588-590 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a cyclic process of Si growth followed by ultraviolet (UV) irradiation which suppresses Si nucleation on the SiO2 surface. We grew Si using low pressure chemical vapor deposition with a Si2H6/H2 gas system without chlorine at 700 and 650 °C. Incubation period is determined using Auger electron spectroscopy as the time for which there is less than 0.015 coverage of Si on SiO2. We show that intermittent UV irradiation within the incubation period suppresses Si nucleation on the SiO2 surface. We believe the growth/UV-irradiation cyclic process is useful for preparing a thick Si selective epitaxial growth layer.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 1051-1054 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The long-term (1- and 2-year) adverse tissue responses including tumor formation by subcutaneous implanation of polyurethanes (PUS) and silicone (Sil) films intorats were compared. The weight-averaged molecular weights (Mw) of the PUS prepared from 4,4′-diphenylmethanediisocyanate, poly (tetramethyleneglycol) of M, = 1000 and 1,4-butanediol are 220,000 (U-4), 124,000 (U-6), and 55,600 (U-8). The 50:50 mixed film of U-6 and silicone (U-b/sil) was prepared by rollmixing of the noncured silicone and the U-6 solution followed by evaporation of the solvent and heat-curing at 70°C. The tissue responses around implants were classified into four groups as follows: (A) tumor, (B) atypical cell proliferation accompanied by preneoplastic changes, (C) cell proliferation without preneoplastic changes, (D) no obvious responses. In both implantation periods, the PUS gave higher incidents of the adverse responses including tumor formation in comparison to Sil. No significant molecular weightdependent trend was found in a 1-year study using U-4, 6, and 8. Significant PU-dose-dependent trends were found in a 2-year study: the total active incidence (A + B + C), U-6(22/29) 〉 U-6/si1(11/29) 〉 sil(7/28); tumor incidence (A), U-6(11/29) 〉 U-6/si1(2/29) = si1(2/28). No detectable amounts of 4,4′-methylenedianiline (MDA) were found in the PUS. The methanol extracts from the PUS were negative in the mutagenicity tests. These indicate no relationship between the tumor formation by the PU films and the mutagenicities of the chemicals (mainly oligomers) leached from the PUs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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