Adsorption of cobalt phthalocyanine on Si(1 0 0)2 × 1 and Si(1 0 0)2 × 1:H surfaces studied by scanning tunneling microscopy and spectroscopy

Ultra-high vacuum, scanning tunneling microscopy (STM) and spectroscopy (STS) are used to study isolated cobalt phthalocyanine (CoPc) molecules adsorbed on both the Si(1 0 0)2 × 1 surface and single dangling bonds of the Si(1 0 0)2 × 1:H surface. Three major adsorption configurations are observed on the Si(1 0 0)2 × 1 surface consisting of a fourfold molecular image characteristic of CoPc but possessing different central structural features. However, images obtained on the Si(1 0 0)2 × 1:H surface correspond to molecular rotation of CoPc parallel to the surface. STM, STS, current image tunneling spectroscopy and molecular modeling are used to investigate the different interactions between CoPc and these two Si substrates, as well as their effects upon the electronic charge distribution and the geometric configurations of the adsorbed CoPc molecules.