Evidence for one-dimensional electron propagation on Si(111)-(2x1) from Coulomb blockade

Scanning tunneling spectroscopy is used to study the electronic properties of the Si(111)-2x1 surface at 8 K. Wave-function mapping reveals highly anisotropic scattering of electrons with one-dimensional (1D) confinement on the pi-bonded chains. The differential tunneling conductance is strongly reduced at the Fermi energy E-F and exhibits a Coulomb gap. The gap width W scales with the inverse length L of the chain segments defined by the distance between two adjacent scatterers such as surface steps or dopant atoms within a given chain. A model of electronic transport through 1D chain segments of finite length describes the observed behavior.