AVS 47th International Symposium
    Organic Films and Devices Thursday Sessions
       Session OF+EL+SS-ThM

Paper OF+EL+SS-ThM7
Scanning Tunneling Microscopy/Spectroscopy Investigation of the Organic Molecules PTCDA and HBC on Au(100)

Thursday, October 5, 2000, 10:20 am, Room 313

Session: Organic Thin Films
Presenter: T. Fritz, TU Dresden, Institut fuer Angewandte Photophysik, Germany
Authors: T. Fritz, TU Dresden, Institut fuer Angewandte Photophysik, Germany
M. Toerker, TU Dresden, Institut fuer Angewandte Photophysik, Germany
H. Proehl, TU Dresden, Institut fuer Angewandte Photophysik, Germany
F. Sellam, TU Dresden, Institut fuer Angewandte Photophysik, Germany
K. Leo, TU Dresden, Institut fuer Angewandte Photophysik, Germany
Correspondent: Click to Email
Highly ordered organic thin films on gold single crystals have been investigated by Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS) at room temperature. The organic dye molecule perylene-tetracarboxylic-dianhydride (PTCDA) has been deposited as submonolayer coverage on Au(100). I-V-spectroscopy at fixed tip-sample-separations has been performed alternately on the PTCDA islands and on uncovered areas of the Au(100) surface. The corresponding normalized derivatives of these I-V-curves have then been compared to inverse photoelectron spectroscopy data known from literature, indicating resonant tunneling via the lowest unoccupied molecular orbital. As a second molecule peri-hexabenzocorone (HBC), also deposited on Au(100), has been investigated. The Au(100) surface has been fully covered by a few monolayers thick, highly ordered HBC film. The normalized derivatives of I-V-curves measured on these films show a pronounced local maximum at a negative voltage of about -1.4 V. By comparison with ultraviolet photoelectron spectroscopy (UPS) measurements of HBC on Au(111) we can show that this peak in the tunneling spectroscopy plot is due to resonant tunneling via the highest occupied molecular orbital of HBC.