The adsorption of individual metal-free phthalocyanine molecules on the 6H-SiC(0001)3×3 surface was studied using the scanning tunneling microscope supported by density functional theory calculations. Phthalocyanine molecules were found to be chemisorbed through a reaction of two conjugated imide groups with two silicon adatoms. This type of anchoring opens numerous perspectives for the organic functionalization of a biocompatible wide band gap semiconductor.
Équipe 102 : Surfaces et SpectroscopiesInternational audienceThe ultimate miniaturization of electronic devices at the atomic scale with single electrons requires controlling the reversible charge storage in a single atom. However, reversible charge storage is difficult to control as usually only one charge state can be stabilized. Here, combining scanning tunneling microscopy (STM) and density functional theory (DFT), we demonstrate that a single silicon dangling bond of a hydrogenated p-type doped Si(100) surface has two stable charge states (neutral and negatively charged) at low temperature (5 K). Reversible charge storage is achieved using a gate electric field between the STM tip and the surface
At low temperature (5 K), a single biphenyl molecule adsorbed on a Si(100) surface behaves as a bistable device which can be reversibly switched by electronic excitation with the scanning tunneling microscope tip. Density functional theory suggests that the biphenyl molecule is adsorbed with one dissociated hydrogen atom bonded to a neighbor surface silicon atom. By desorbing this hydrogen atom with the STM tip, the interaction of the molecule with the surface is modified such that it becomes transformed into a multistable device with four stable states having switching yields increased by almost 2 orders of magnitude.
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