The conductivity of Bi(111) investigated with nanoscale four point probes

The room temperature conductance of Bi(111) was measured using microscopic four point probes with a contact spacing down to 500 nm. The conductance is remarkably similar to that of the bulk, indicating that surface scattering is not a major mechanism for restricting the mobility at this length scale. Also, the high density of electronic surface states on Bi(111) does not appear to have a major influence on the measured conductance. The lower limit for the resistivity due to electronic surface states is found to be around 5 Omega. With such a value for the surface resistivity, surface conduction should not be a significant factor to inhibit the observation of the predicted semiconductor to semimetal transition for thin films of Bi. (C) 2008 American Institute of Physics.