Adsorption Of Lead Phthalocyanine On The Ge(111)-C( 2x8) Surface

The adsorption of lead phthalocyanine on the clean Ge(111) surface has been studied with photoelectron spectroscopy and scanning tunnelling microscopy. A strong interaction of the molecule with the surface has been observed through changes in the Pb 5d and C 1s core levels of the adsorbate, plus the Ge 3d core level of the substrate. This interaction can also reduce Pb from the phthalocyanine macrocycle from a 2+ to a neutral state. It is demostrated through STM that this interaction is strongest at defect sites and step edges, and in fact on the unperturbed c(2 X 8) reconstruction, which dominates the surface, the molecules are seen to be significantly mobile at room temperature. This shows a dramatic passivating effect of this reconstruction when compared with other similar semiconductor surfaces.