Reversible Switching of Single Tin Phthalocyanine Molecules on the InAs(111)A Surface
C. Nacci, K. Kanisawa, S. Fölsch
J. Phys. Condensed Matter (2012) accepted for publication
Abstract: Individual tin phthalocyanine (SnPc) molecules adsorbed on the InAs(111)A surface were studied by low-temperature scanning tunnelling microscopy (STM) at 5 K. Consistent with the nonplanar molecular structure, SnPc adopts two in-plane adsorption geometries with the centre Sn atom either above (SnPcup) or below (SnPcdown) the molecular plane. Depending on the current and bias applied to the tunnel junction, the molecule can be reversibly switched between the two conformations, implying a controlled transfer of the Sn atom through the molecular plane. The SnPcdown conformer is characterized by an enhanced surface bonding compared to the SnPcup conformer. SnPcup molecules can be repositioned by the STM tip by means of lateral manipulation, whereas this is not feasible for SnPcdown molecules. The reversible switching process thus enables to either laterally move the molecule or to anchor it to the semiconductor surface.