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VPE preparation of vicinal Si(100): in situ RA spectra and benchmarking to surface science in UHV. During annealing under flow at 1250 K (upper panel), the still oxidized substrate exhibits a featureless signal (thin black line) until the spectrum assigned to clean vicinal Si(100) (thick red line) evolves. Cooling to 300 K at the end of the VPE process (lower panel) leads to a RAS signature associated with monohydride surface, which could be characterized by LEED and STM (insets) confirming a diffraction pattern (left) and type steps (right).
In situ RAS investigation of vicinal Si(100) while cooling from 1270 to 670 K under flow. Spectra measured every 100 K (thin lines) show the transformation from clean vicinal Si(100) (thick red line) to a monohydride termination of the surface (thick blue line). Hydrogen adsorption is accompanied by a decay of signal intensity around 2.5 eV (large arrow) and the formation of a characteristic shoulder around 3.4 eV. Due to decreasing temperature, the spectra are also subject to thermal shifts and sharpening of the features (small arrow).
In situ RAS observation of successive hydrogen desorption from vicinal Si(100). At the constant temperature of 770 K, switching the process gas to a ambient induces successive loss of hydrogen bonds. The initial monohydride termination at (thick blue line) successively transforms (thin gray line) until reaching the constant state of clean vicinal Si(100) (thick red line) after about 35 min.
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