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  • 1
    Electronic Resource
    Electronic Resource
    High room-temperature hole mobility in Ge0.7Si0.3/Ge/Ge0.7Si0.3 modulation-doped heterostructures (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2497-2499 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Modulation-doped two-dimensional hole gas structures consisting of a strained germanium channel on relaxed Ge0.7Si0.3 buffer layers were grown by molecular-beam epitaxy. Sample processing was optimized to substantially reduce the contribution from the parasitic conducting layers. Very high hall mobilities of 1700 cm2/V s for holes were observed at 295 K which are the highest reported to date for any kind of p-type silicon-based heterostructures. Hall measurements were carried out from 13 to 300 K to determine the temperature dependence of the mobility and carrier concentration. The carrier concentration at room temperature was 7.9×1011 cm−2 and decreased by only 26% at 13 K, indicating very little parallel conduction. The high-temperature mobility obeys a T−α behavior with α∼2, which can be attributed to intraband optical phonon scattering. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1334632
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  • 2
    Electronic Resource
    Electronic Resource
    Alloy scattering limited transport of two-dimensional carriers in strained Si1−xGex quantum wells (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 2795-2797 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The mobility of two-dimensional electron systems in strained Si1−xGex quantum wells was studied at low temperatures as a function of the germanium content in the well. While mobilities exceeding 30 000 cm2/V s have been achieved for pure Si layers, they dropped to less than 3000 cm2/V s for Si0.88Ge0.12 wells, demonstrating the effect of strong alloy disorder scattering. This was confirmed by the relatively weaker dependence of mobility on carrier concentration in gating experiments. By accounting for valley degeneracy effects in the standard two-dimensional alloy scattering model, an effective scattering potential Valloy=0.8±0.1 eV has been derived for electrons. Using a weaker potential, it is shown that the maximum low temperature mobilities for holes reported in literature are also consistent with the alloy scattering model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110337
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  • 3
    Electronic Resource
    Electronic Resource
    Symmetric Si/Si1−xGex two-dimensional hole gases grown by rapid thermal chemical vapor deposition (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2871-2873 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single and symmetric double p-type modulation-doped structures have been fabricated in Si/SiGe for the first time by rapid-thermal chemical-vapor deposition. Temperature-dependent electrical measurements and high-field magnetotransport measurements demonstrate the presence of a well-confined two-dimensional hole gas in these samples. Nominally-symmetric normal and inverted structures differ in carrier density and mobility at most by 20%, indicating that there is little asymmetry due to surface segregation or autodoping effects. Measurements on double heterostructures confirm that the interfaces are symmetric to within 10 A(ring). Peak mobilities reached 2500 cm2/V s at 10 K, comparable to those obtained in similar samples grown by ultrahigh vacuum techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105837
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  • 4
    Electronic Resource
    Electronic Resource
    High-mobility InSb epitaxial films grown on a GaAs (001) substrate using liquid-phase epitaxy (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2102-2104 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth of epitaxial InSb layers on highly lattice-mismatched semi-insulating GaAs substrates has been achieved via traditional liquid-phase epitaxy. Scanning and transmission electron microscopy show sharp interfaces even at 35 nm resolution. High-resolution x-ray diffraction studies reveal reflections even up to 2θ=153° with distinct layer and substrate peaks, indicating structural coherence. The films grown were n type and the highest electron mobility obtained was 3.96×104 cm2/V s at room temperature. The band gap varies from 0.17 to 0.23 eV in the temperature range of 300–10 K and is consistent with the expected variation. These results indicate that the films grown are comparable to those grown by other sophisticated techniques in terms of structural, optical and electrical properties. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1458066
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of strain in Si1−xGex films using multiple angle of incidence ellipsometry (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3529-3531 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter we characterize strain in Si1−xGex based heterojunction bipolar transistors and modulation doped field effect transistors grown by rapid thermal chemical vapor deposition exploiting the phenomenon of strain-induced birefringence. The technique used is multiple angle of incidence ellipsometry at a wavelength of 670 nm to measure the ordinary and extraordinary refractive indices of the Si1−xGex films. We report measurements on thin fully strained films (with thicknesses less than the critical thickness) with Ge concentration varying from 9% to 40% with an accuracy of the order of 1 part in 104 and propose an empirical relation between the difference in the ordinary and extraordinary refractive indices (δn) and the Ge concentration (x) given by δn(x)=0.18x−0.12x2. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1329165
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  • 6
    Electronic Resource
    Electronic Resource
    Transcriptional regulation of an unusual trypsin-related protein expressed during insect metamorphosis
    Amsterdam : Elsevier
    Insect Biochemistry and Molecular Biology 23 (1993), S. 825-829 
    Details
    ISSN: 0965-1748
    Keywords: Juvenile hormone ; Trichoplusia ni
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0965-1748(93)90071-Y
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