Threshold height for movement of C60 molecules on Si(111)-7×7 with a scanning tunneling microscope

Abstract

Scanning tunneling microscope has been employed for intentional movement of C60 molecules adsorbed on Si(111)-7×7 surface. Threshold conditions at which a C60 molecule starts moving from its adsorption site are investigated in relation to tunnel current and tip bias voltage. We find that there exists threshold height for the movement process. The threshold height estimated from a planar electrode model is in agreement with the vertical height of the adsorbed C60 molecules. Present results evidence that direct contact or close proximity between a mechanical probe and C60 molecules is required for movement of the molecules to occur.