Epitaxial growth of 3,4,9,10-perylene-tetracarboxylic-dianhydride on Au(111): A STM and RHEED study

The crystal structure of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) grown by organic molecular-beam epitaxy on reconstructed Au(111) surfaces is investigated by scanning tunneling microscopy and reflection high-energy electron diffraction. Large domains of PTCDA (up to 200 nm) are found on the still reconstructed Au surface. The reconstruction can be used to precisely determine the lattice orientation of the PTCDA layers. Three different orientations with respect to the gold substrate were observed. All of them can be explained in terms of a point-on-line growth model that was originally proposed for explaining organic epitaxy results on graphite.