Reaction of a Si (100) surface with a hot C₂H₄ beam

A clean Si(100) surface at 670°C in ultrahigh vacuum was irradiated with a C₂H₄ molecular beam produced from a nozzle at 900°C. The reaction products on the surface were investigated using X-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning electron microscopy. The central area of the surface irradiated with the beam was covered with a mixture of graphitic film and SiC grains. At the fringe of the central area, however, the SiC grains were the dominant products, which were epitaxially grown on the Si(100) surface. The density of the SiC grains decreased with the distance from the fringe. Compared with the results using the molecular beam produced from the nozzle at room temperature, it is concluded that the dissociation rate of the hot C₂H₄ molecules is higher than that of the cold molecules, resulting in a carbon film. The growth mechanisms of the graphitic and SiC products are discussed.