MOLECULAR ARRANGEMENT OF COPPER PHTHALOCYANINE ON HYDROGEN-TERMINATEDSI(111) - INFLUENCE OF SURFACE-ROUGHNESS

The molecular arrangement of copper phthalocyanine (CuPc) crystals on hydrogen-terminated Si(lll) surfaces was investigated by using both sc anning probe microscopy and x-ray diffraction in terms of influence of the surface roughness, On a rough surface with a root-mean-square rou ghness of 0.20 nm, the molecules were stacked so as to form an a cryst al where the molecular column was parallel to the surface. On the othe r hand, a new crystal form with its column exactly perpendicular to th e Si(lll) plane was grown on a atomically flat surface. In this case, the molecules were stacked perpendicular to the substrate with the und erlying molecules situated directly below. These molecular arrangement s were independent of the growth temperature in the range of 60-180 de grees C. On the atomically flat surfaces, the strong interactive force between the surface and the planar CuPc molecule may result in the ne w growth behavior. (C) 1996 American Vacuum Society.