Large surface-state conductivity in ultrathin Bi films

In situ microscopic-four-point probe conductivity measurements were performed for ultrathin Bi films on Si(111)-7x7. From the extrapolation of thickness-dependent conductivity and decrease in conductivity through surface oxidization, we found clear evidence of large surface-state conductivity (sigma(SS)similar to 1.5x10(-3) Omega(-1)/square at room temperature) in Bi(001) films. For the thinnest films (similar to 25 A), the transport properties are dominated by the highly inert surface states that are Rashba spin-split, and this suggests the possibility of using these Bi surface states for spintronics device application. (c) 2007 American Institute of Physics.