AVS 45th International Symposium
    Organic Electronic Materials Topical Conference Tuesday Sessions
       Session OE+BI+EM-TuA

Paper OE+BI+EM-TuA4
Preferential Orientation of Copper Phthalocyanine Molecular Columns on Vicinal Si(001)-(2x1)-H

Tuesday, November 3, 1998, 3:00 pm, Room 327

Session: Organic Thin Film Growth
Presenter: H. Tokumoto, JRCAT-NAIR, Japan
Authors: M. Nakamura, JRCAT-ATP, Japan
T. Matsunobe, Toray Research Center, Inc., Japan
H. Tokumoto, JRCAT-NAIR, Japan
Correspondent: Click to Email
Fabrication of Pc films on silicon substrates has an advantage in terms of having electrical interfaces with silicon devices. Furthermore, it is a great scientific interest to study organic film growth on various atomically controlled surfaces utilizing well established methods to prepare clean silicon surfaces with a chemical passivation by hydrogen. In our previous work,@footnote 1@ we investigated the molecular arrangement of CuPc films on atomically flat Si(001)-(2x1)-H. Atomic force microscopy (AFM) showed that the molecular column laid parallel to the surface, and the orientational angle between the column and the substrate <110> directions was around 17°. The angle was also supported by molecular mechanics (MM) simulations using simple atom-atom van der Waals potentials. The results suggested that the CuPc crystals were placed so as to make the linear corrugation of the surface parallel to the substrate H rows, although their periods were still incommensurate with each other. In this work, we therefore used vicinal Si(001)-(2x1)-H as substrates which contain atomic steps of approximately 4 nm period to further control the in-plane orientation. A continuous film of which thickness was distributed within 16.5±2.5 molecular layers was grown at 60°C. 90% of the molecular columns in the film were estimated to be aligned to across the step rows by observing a frictional force image. The preferential orientation is considered to be due to a kind of artificial surface lattices which are formed with the striped 'effective contact area' between the rigid Pc crystals and the vicinal surfaces. Detailed discussions and optical property of the films will be presented. @FootnoteText@ @footnote 1@M. Nakamura and H. Tokumoto, Surf. Sci. 398 (1998) 143.