Electrical Resistance of a Monatomic Step on a Crystal Surface

We have succeeded in measuring the resistance across a single atomic step through a monatomic-layer metal on a crystal surface, Si(111)(√3×√3)-Ag, using three independent methods, which yielded consistent values of the resistance. Two of the methods were direct measurements with monolithic microscopic four-point probes and four-tip scanning tunneling microscope probes. The third method was the analysis of electron standing waves near step edges, combined with the Landauer formula for 2D conductors. The conductivity across a monatomic step was determined to be about 5×10³ Ω^-1 m^-1. Electron transport across an atomic step is modeled as a tunneling process through an energy-barrier height approximately equal to the work function.