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1 September 1991 Growth and characterization of ultrathin SimGen strained-layer superlattices
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Growth of ultrathin SimGen [m monolayers (ML) Si, n ML Ge] strained layer superlattices (SLS) by molecular beam epitaxy is reported. Diode structures (doping sequence p+-n-n+ on n+-substrate and n+-n-p+ on p+-substrate) were grown for optical device applications where strain symmetrization of the SLS by a thin homogeneous buffer layer was used. The concepts of bandstructure folding and strain adjustment of the SLS by a thin (approximately 50 nm) Si1-ybGeyb alloy buffer layer are described. The folded bandstructure with its transition matrix elements as a function of period length is calculated. Various characterization tools such as x-ray diffraction, transmission electron microscopy, Rutherford backscattering, Raman spectroscopy, and photocapacitance measurements are used to analyze the growth quality, strain distribution, periodicity, interface sharpness, and optical properties of the superlattice. Results from recent optical experiments such as photoluminescence and ellipsometry giving hints of a direct bandgap transition in a 10 ML Si6Ge4 SLS in the near-infrared spectral region (hwapproximately equals 0.8 eV) are compared with PL data from SiGe alloys. Device applications offering the possibility of a monolithic integration of superlattice devices with complex silicon based electronic circuits are discussed.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hartmut Presting, Milan Jaros, and Gerhard Abstreiter "Growth and characterization of ultrathin SimGen strained-layer superlattices", Proc. SPIE 1512, Infrared and Optoelectronic Materials and Devices, (1 September 1991);


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