Using Fourier transform infrared-attenuated total reflectance spectroscopy in conjunction with hydrogen adsorption to probe surface layer composition, we observe a reversible place exchange between Ge and Si on Ge-covered Si(001) when the surface is dosed with atomic H at elevated temperatures. First-principles calculations confirm a thermodynamic driving force for this place exchange. To explain the intriguing kinetics of the place exchange, which shows no time dependence, we propose a dimervacancy diffusion-assisted mechanism limited by vacancy interactions. [S0031-9007(98)
We show that it is possible to extend the lower limit of the spectral range of Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy on Si surfaces from 1500 to ∼850 cm−1 using a Ge ATR prism coated with a thin epitaxial layer of Si, making accessible the especially important fingerprint region of organic molecules. The utility of the ATR prism is demonstrated by collecting FTIR spectra of several surface terminations of Si (H, oxide, 3-aminopropyltrimethoxysilane, and DNA) that contain peaks in the newly accessible spectral region.
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