XPS and STM study of SiC synthesized by acetylene and disilane reaction with the Si(1 0 0)2 × 1 surface

The SiC formation on a ordered Si(1 0 0) substrate at low temperatures (980-1180 K) and low total pressures (10−6 mbar) has been investigated by in situ X-ray photoemission spectroscopy (XPS) and ex situ scanning tunneling microscopy (STM). SiC was grown by chemical vapor deposition (CVD) from C2H2 and Si2H6 as the precursor gases. At all the temperatures and in presence of both C2H2 and Si2H6 XPS data showed the formation of sub-stoichiometric Si1−xCx alloys characterized by excess silicon. By exposing to C2H2 only, stoichiometric SiC could be synthesized up to 1080 K. At 1180 K the formation of a Si1−xCx alloy was observed. STM analysis has pointed out the role of silicon from the gas phase in the growth mechanisms and it has shown that uniform films with low roughness and small nanostructures can be obtained by tuning the acetylene/disilane ratios independently from the temperature selected in the investigated range.