Nanometer-size Au clusters deposited from a cluster beam onto a thin dithiol film were studied at room temperature using an ultrahigh vacuum scanning tunneling microscope (STM). The dithiol molecules tether the deposited Au clusters to the underlying gold substrate and repeatable STM scans of the Au clusters were achieved. Data of the tunneling current as a function of applied voltage yield reproducible evidence for single electron tunneling at room temperature. By fitting the measured I(V) data to a Coulomb blockade model, estimates for the electrical resistance of a single dithiol molecule are also obtained.

• Received 12 April 1995

DOI:https://doi.org/10.1103/PhysRevB.52.9071