Role of hydrogen in the initial stage of diamond heteroepitaxy on silicon

The reaction of atomic hydrogen with the (Formula presented)(Formula presented)-covered Si surface was studied using high-resolution electron-energy-loss spectroscopy (HREELS), thermal-desorption mass spectrometry (TDMS), and low-energy electron diffraction. We found that atomic hydrogen broke up the carbon-carbon bond in (Formula presented)(Formula presented) and the Si-Si dimers on the Si surface, which led to the formation of C-H and Si-H bonds, respectively. When the (Formula presented)(Formula presented)-covered Si(100) surface was exposed to a filament-activated (Formula presented)/(Formula presented) mixture, HREELS showed that the C-H stretching signal grew at the expense of the Si-H stretching signal. This observation was consistent with the replacement of the Si-H bond by -(Formula presented), possibly following hydrogen abstraction from the Si-H bond by atomic hydrogen. TDMS analysis showed significant desorption of atomic hydrogen at both 650 and 750 K and a little desorption of (Formula presented) and (Formula presented) only at 650 K, although HREELS remained unchanged with annealing temperature. This showed that part of the hydrocarbon species on the Si surface existed as a stable network of hydrocarbon, which possibly was the initial stage of diamond formation on Si. © 1996 The American Physical Society.