Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 40: Transport: Molecular Electronics I (TT jointly with O)
O 40.3: Vortrag
Mittwoch, 2. April 2014, 10:00–10:15, HSZ 304
Gate-controlled shift of CoPc orbitals on graphene in a STM junction — •Samuel Bouvron1, Philipp Erler1, Alexander Graf1, Romain Maurand2, Luca Gragnaniello1, Dirk Wiedmann1, Fabian Pauly1, and Mikhail Fonin1 — 1Fachbereich Physik, Universität Konstanz — 2Department of Physics, University of Basel
One of the most promising aims of molecular electronics is the fabrication of a molecular transistor. Such a device necessarily requires a gate-electrode, which allows to set the molecule into a controllable electric field, therefore tuning the energy of the molecular orbitals relevant for charge transport. Moreover since the very first year of the development of the scanning tunneling microscope (STM), it has been proposed to use its extremely high lateral resolution to study molecules and record I(V) or I(z) characteristics of the tunnel contacts formed. However, the geometric constrains of the microscope make the implementation of a third gate-electrode challenging. Here we investigate the electronic properties of cobalt phthalocyanine (CoPc) molecules on graphene on SiO2/Si, where graphene and Si serve as drain and gate electrode, respectively. We report on site-dependent and gate-dependent tunnel transport through the CoPc molecules. The influence of the gate voltage on the energy position of the molecular orbitals is discussed and the orbital structure is assigned. Finally this STM-tip/molecule/graphene/SiO2/Si device geometry opens a possibility to combine the spatial resolution of the STM with the additional control of the electric field commonly used in transport measurements.