NASA Technical Reports Server (NTRS) : Spectroscopic pdf

NASA Technical Reports Server (NTRS) : Spectroscopic

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Spectroscopic ellipsometry (SE) was employed to characterize Si/Si(1-x)Ge(x) strained-layer superlattices. An algorithm was developed, using the available optical constants measured at a number of fixed x values of Ge composition, to compute the dielectric function spectrum of Si(1-x)Ge(x) at an arbitrary x value in the spectral range 17 to 5.6 eV. The ellipsometrically determined superlattice thicknesses and alloy compositional fractions were in excellent agreement with results from high-resolution x ray diffraction studies. The silicon surfaces of the superlattices were subjected to a 9:1 HF cleaning prior to the SE measurements. The HF solution removed silicon oxides on the semiconductor surface, and terminated the Si surface with hydrogen-silicon bonds, which were monitored over a period of several weeks, after the HF cleaning, by SE measurements. An equivalent dielectric layer model was established to describe the hydrogen-terminated Si surface layer. The passivated Si surface remained unchanged for greater than 2 h, and very little surface oxidation took place even over 3 to 4 days

• Creator/s: NASA Technical Reports Server (NTRS
• Date: 8/1/1993
• Year: 1993
• Book Topics/Themes: NASA Technical Reports Server (NTRS), ELLIPSOMETRY, OXIDATION, SILICON COMPOUNDS, SPECTROSCOPY, SUPERLATTICES, SURFACE LAYERS, CHEMICAL COMPOSITION, DIELECTRIC PROPERTIES, HYDROGEN BONDS, THICKNESS, Yao, H., Woollam, J. A., Wang, P. J., Tejwani, M. J., Alterovitz, S. A

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