Conductivity of Si(111)-(7 77): The role of a single atomic step

While it is known that the Si-(7 77) is a conducting surface, measured conductivity values differ by 7 orders of magnitude. Here we report a combined STM and transport method capable of surface conductivity measurement of step-free or single-step containing surface regions and having minimal interaction with the sample, and by which we quantitatively determine the intrinsic conductivity of the Si-(7 77) surface. We found that a single step has a conductivity per unit length about 50 times smaller than the flat surface. Our first principles quantum transport calculations confirm and lend insight into the experimental observation. \ua9 2014 American Physical Society.Peer reviewed: YesNRC publication: Ye