Anomalous electron tunneling through a Ag island on the GaAs(110) surface observed by the current image tunneling spectroscopy (CITS)

Using scanning tunneling microscopy, Coulomb blockade of tunneling electrons was realized on a simple metal/semiconductor system, by taking a sample of individual Ag clusters formed on the clean GaAs(110) surface. The second barrier of a two tunneling junction is at a space interval at the Ag/GaAs(110) interface, which is naturally formed due to a lattice match of the cluster and the GaAs(110) substrate. Images of differential conductance taken of the clusters by current image tunneling spectroscopy (CITS) demonstrate that the electron tunneling is closely related to detailed atomic structures of the clusters.