Scanning tunneling microscopy study of Fe(CO)5 and Fe(C5H5)2 adsorption on Si(111)7×7 and B/Si(111)√3×√3

The adsorption at room temperature of ferrocene and iron pentacarbonyl on Si(111)7×7 and B/Si(111)√3×√3 R30° have been studied. On Si(111)7×7, the adsorption sites have been identified by means of scanning tunneling microscopy. We propose a ferrocene adsorption model on Si(111)7×7, i.e., a di-sigma bridging by the molecule between an adatom and a restatom site similar to that proposed for the ethylene. This process is in agreement with the lack of reactivity of this molecule on the B/Si(111)√3×√3 R30° surface. For the iron pentacarbonyl, we have found evidence of a dissociative adsorption on nucleophilic sites. At a higher temperature, an exposure to iron pentacarbonyl lead to the growth of good quality iron silicide. Whereas, silicide carbide is formed on exposure to ferrocene. The films obtained can be explained by means of the chemisorption process at room temperature.