Croke, E. T. and Vajo, J. J. and Hunter, A. T. and Ahn, C. C. and Chandrasekhar, D. and Laursen, T. and Smith, David J. and Mayer, J. W. (1998) Stabilizing the surface morphology of Si1–x–yGexCy/Si heterostructures grown by molecular beam epitaxy through the use of a silicon-carbide source. Journal of Vacuum Science and Technology B, 16 (4). pp. 1937-1942. ISSN 1071-1023 http://resolver.caltech.edu/CaltechAUTHORS:CROjvstb98
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Si1–x–yGexCy/Si superlattices were grown by solid-source molecular beam epitaxy using silicon carbide as a source of C. Samples consisting of alternating layers of nominally 25 nm Si1–x–yGexCy and 35 nm Si for 10 periods were characterized by high-resolution x-ray diffraction, transmission electron microscopy (TEM), and Rutherford backscattering spectrometry to determine strain, thickness, and composition. C resonance backscattering and secondary ion mass spectrometries were used to measure the total C concentration in the Si1–x–yGexCy layers, allowing for an accurate determination of the substitutional C fraction to be made as a function of growth rate for fixed Ge and substitutional C compositions. For C concentrations close to 1%, high-quality layers were obtained without the use of Sb-surfactant mediation. These samples were found to be structurally perfect to a level consistent with cross-sectional TEM (< 10^7 defects/cm^2) and showed considerably improved homogeneity as compared with similar structures grown using graphite as the source for C. For higher Ge and C concentrations, Sb-surfactant mediation was found to be required to stabilize the surface morphology. The maximum value of substitutional C concentration, above which excessive generation of stacking fault defects caused polycrystalline and/or amorphous growth, was found to be approximately 2.4% in samples containing between 25 and 30% Ge. The fraction of substitutional C was found to decrease from roughly 60% by a factor of 0.86 as the Si1–x–yGexCy growth rate increased from 0.1 to 1.0 nm/s.
|Additional Information:||©1998 American Vacuum Society. (Received 9 September 1997; accepted 18 May 1998) Partial support for this work was provided by the Defense Advanced Research Projects Agency (DARPA) monitored by Lt. Col. Gernot Pomrenke under Contract No. MDA972-95-3-0047. Presented at the Silicon Heterostructures Conference, Barga, Italy, 15–19 September 1997.|
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|Deposited On:||23 Apr 2006|
|Last Modified:||26 Dec 2012 08:50|
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