Autocatalytic growth of Co on pure Co surfaces using Co2(CO)8 precursor

The autocatalytic growth of Co on different surfaces using the Co2(CO)8 precursor is investigated. It is observed that Co2(CO)8 molecules dissociate spontaneously on pure Co surfaces grown by sputtering, forming a pure Co film. The microstructure of this film consists of Co nanocrystals with size below 100 nm. However, when the same type of experiment is done on a Co surface grown by focused-electron-beam induced deposition there is no autocatalytic growth of Co. On other surfaces such as Si substrates and Al films grown by sputtering, the spontaneous dissociation of the Co2(CO)8 molecules does not occur. The origin and implications of these results are discussed.