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  • 1
    Electronic Resource
    Electronic Resource
    The influence of age on prognosis in carcinoma of the cervix (1987)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 94 (1987), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. Of 385 new patients with invasive carcinoma of the cervix FIGO stages IB—IV treated between 1970–1984 inclusive, 11% (43 patients) were aged ≤35 years. During the period studied there was a gradual rise in the proportion of such young women from 2% for the triennium 1970–1972 to 18% for 1982–1984. In women aged ≤35 years early stage disease predominated, 72% presenting with stage IB disease, compared with 29% in the older age group. For FIGO stage IB there was no significant difference in actuarial survival between younger and older patients (P〉0·1), both age groups having a 5-year survival rate of 81%. Similarly for FIGO stage II there was no difference in actuarial survival (P〉0·1) between younger and older patients who had 5-year survival rates of 66% and 63% respectively. In our experience the incidence of invasive carcinoma of the cervix in young women is rising, but stage for stage their survival is similar to that of older women.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1987.tb03727.x
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  • 2
    Electronic Resource
    Electronic Resource
    Left atrial myxoma in the second trimester of pregnancy. Case report (1987)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 94 (1987), 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.1471-0528.1987.tb03156.x
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  • 3
    Electronic Resource
    Electronic Resource
    Impurity-induced layer disordering in In0.5(Alx Ga1−x)0.5P-InGaP quantum-well heterostructures: Visible-spectrum-buried heterostructure lasers (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 482-487 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diffusion of Si into quantum-well heterostructures and superlattices employing the high gap III-V quaternary system Iny (AlxGa1−x )1−yP is shown to result in impurity-induced layer disordering. Secondary ion mass spectroscopy, transmission electron microscopy, and photoluminescence data indicate that the diffusion of Si into an InAlP-InGaP superlattice grown lattice matched on GaAs (y≈0.5) results in the intermixing of the layers, thus forming an alloy of average composition. Buried-heterostructure lasers are fabricated using Si layer disordering of In0.5 (Alx Ga1−x )0.5 P p-n quantum-well heterostructures. The disorder-defined stripe-geometry diode lasers operate pulsed at 300 K near 6400 A(ring). Continuous wave operation at λ∼6255 A(ring) is achieved at −47 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343562
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  • 4
    Electronic Resource
    Electronic Resource
    Impurity diffusion and layer interdiffusion in AlxGa1−xAs-GaAs heterostructures (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1838-1844 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented and a model describing the diffusion of the donor Si in GaAs from grown-in dopant sources. In addition, the effects of background impurities on Si diffusion and layer interdiffusion in AlxGa1−xAs-GaAs superlattices are described. These results are obtained on epitaxial GaAs samples with alternating doped and undoped layers and on AlxGa1−xAs-GaAs superlattices with doped (Si or Mg) layers. The layer-doped GaAs and the AlxGa1−xAs-GaAs superlattices have been grown using metalorganic chemical vapor deposition and are characterized using secondary ion mass spectroscopy and transmission electron microscopy. Different annealing conditions are used to study the interaction between the grown-in impurities and the native defects of the crystal controlling the diffusion processes. The model describing the impurity diffusion and layer (Al-Ga) interdiffusion is based on the behavior of column III vacancies, VIII, and column III interstitials, IIII, and the control of their concentration by the position of the crystal Fermi level and the crystal stoichiometry. Experimental data show that n-type AlxGa1−xAs-GaAs superlattices undergo enhanced layer interdiffusion because of increased solubility of the VIII defect, while enhanced layer interdiffusion in p-type superlattices is caused by an enhanced solubility of IIII. The model employed is consistent with the experimental data and with the data of previous work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341759
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  • 5
    Electronic Resource
    Electronic Resource
    Defect-accelerated donor diffusion and layer intermixing of GaAs/AlAs superlattices on laser-patterned substrates (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5821-5825 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented showing that donor diffusion and Alx Ga1−x As-GaAs layer intermixing are greatly enhanced in the presence of defects created by crystal overgrowth on locally laser-melted substrates. Accelerated defect and impurity-induced layer disordering, and donor diffusion from a solid source (SiO2 ), a vapor source (Ge), and from a grown-in source (Se) are observed in regions of high defect density. The enhanced donor diffusion and crystal self-diffusion are attributed to an increased density of column-III defects and dislocations in the crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343653
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  • 6
    Electronic Resource
    Electronic Resource
    An investigation of the annihilated unrestricted Hartree–Fock wave function and its use in second-order Møller–Plesset perturbation theory (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1789-1795 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The recently introduced annihilated unrestricted Hartree–Fock (AUHF) wave function—in which the first spin contaminant in an unrestricted Hartree–Fock (UHF) wave function has been annihilated self-consistently—is discussed in some detail with particular attention to its use as a basis for a perturbation expansion. A series of calculations are presented highlighting the advantages and disadvantages of a second-order Møller–Plesset (AUMP2) perturbation treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457084
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  • 7
    Electronic Resource
    Electronic Resource
    Carbon diffusion in undoped, n-type, and p-type GaAs (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 687-689 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of background doping, surface encapsulation, and As4 overpressure on carbon diffusion have been studied by annealing samples with 1000 A(ring) p-type carbon doping spikes grown within 1 μm layers of undoped (n−), Se-doped (n+), and Mg-doped (p+) GaAs. The layers were grown by low-pressure metalorganic chemical vapor deposition using CCl4 as the carbon doping source. Two different As4 overpressure conditions were investigated: (1) the equilibrium pAs4 over GaAs (no excess As), and (2) pAs4 ∼2.5 atm. For each As4 overpressure condition, both capless and Si3N4-capped samples of the n−-, n+-, and p+-GaAs crystals were annealed simultaneously (825 °C, 24 h). Secondary-ion mass spectroscopy was used to measure the atomic carbon depth profiles. The carbon diffusion coefficient is always low, but depends on the background doping, being highest in Mg-doped (p+) GaAs and lowest in Se-doped (n+) GaAs. The influence of surface encapsulation (Si3N4) and pAs4 on carbon diffusion is minimal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101822
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  • 8
    Electronic Resource
    Electronic Resource
    Disorder-defined buried-heterostructure AlxGa1−xAs-GaAs quantum well lasers by diffusion of silicon and oxygen from Al-reduced SiO2 (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1265-1267 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a convenient method utilizing chemical reduction of SiO2 by Al (from AlxGa1−xAs) to generate Si and O for impurity-induced layer disordering (IILD) of AlxGa1−xAs-GaAs quantum well heterostructures (QWHs). Experimental data show that Si-O diffusion (from SiO2) is an effective source of Si for Si-IILD and of O that compensates the Si donor, thus resulting in higher resistivity layer-disordered crystal. The usefulness of the Si-O IILD source for fabricating low-threshold disorder-defined buried-heterostructure AlxGa1−xAs-GaAs QWH lasers is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100734
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  • 9
    Electronic Resource
    Electronic Resource
    Sensitivity of Si diffusion in GaAs to column IV and VI donor species (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 129-131 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Secondary ion mass spectroscopy and carrier concentration measurements are used to characterize Si diffusion into GaAs wafers containing two fundamentally different forms of donors, the column IV donors Si or Sn and the column VI donors Se or Te. A decrease in the Si diffusion rate is found in GaAs containing the column VI donors compared to the column IV donors. This trend is consistent with the model in which the Si diffuses as donor-gallium-vacancy complexes. The decrease in the Si diffusion coefficient is attributed to the greater binding energy of column VI donor-gallium-vacancy nearest-neighbor complexes, thus reducing the concentration of free-gallium vacancies available to complex with the Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99072
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  • 10
    Electronic Resource
    Electronic Resource
    Heavy carbon doping of metalorganic chemical vapor deposition grown GaAs using carbon tetrachloride (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1905-1907 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A mixture of 500 ppm CCl4 in H2 has been used to grow heavily doped p-type GaAs by low-pressure metalorganic chemical vapor deposition with TMGa and AsH3 as the group III and V sources, respectively. Carbon acceptor concentrations between 1×1016 and 1×1019 cm−3 were obtained. In addition, abrupt carbon-doping profiles were achieved with no noticeable memory effects. Carrier concentration was studied as a function of CCl4 flow, V/III ratio, growth temperature, and growth rate using electrochemical capacitance-voltage profiling. Carbon incorporation was found to depend on CCl4 flow, V/III ratio, and growth temperature. Carbon incorporation had no dependence on the growth rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101237
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