Scanning tunneling microscopy and spectroscopy investigations of copper phthalocyanine adsorbed on Al2O3/Ni3Al(111)

M. Moors, A. Krupski, S. Degen, M. Kralj, C. Becker, K. Wandelt

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Low temperature scanning tunneling microscopy (LT-STM) and scanning tunneling spectroscopy (STS) have been used to investigate adsorbed copper phthalocyanine (C32H16N8Cu) molecules on an ordered ultrathin Al2O3 film on the Ni3Al(1 1 1) surface as a function of coverage and annealing temperature. For sub-monolayer coverage and a deposition temperature of 140 K two different planar molecular adsorption configurations rotated by 30° with respect to each other were observed with submolecular resolution in the STM images. The template effect of the underlying oxide film on the CuPc orientation, however, is only weak and negligible at higher coverages. For θCuPc ≈ 1 ML, before completion of the first layer, the growth of a second layer was already observed. The measured spacing of 3.5 Å between first and second layer corresponds to the distance between the layers in the α-modification of crystalline CuPc. The molecules deposited at 140 K are thermally stable upon prolonged annealing to temperatures up to 250 K. By the use of STS the lowest unoccupied molecular orbital (LUMO) of the adsorbed copper phthalocyanine molecules has been identified at an energy of 1.2 eV above EF. The lateral distribution of the electronic states of the CuPc has been analyzed and mapped by STS.
    Original languageEnglish
    Pages (from-to)4251-4257
    JournalApplied Surface Science
    Volume254
    Issue number14
    DOIs
    Publication statusPublished - 15 May 2008

    Fingerprint

    Dive into the research topics of 'Scanning tunneling microscopy and spectroscopy investigations of copper phthalocyanine adsorbed on Al<sub>2</sub>O<sub>3</sub>/Ni<sub>3</sub>Al(111)'. Together they form a unique fingerprint.

    Cite this