Surface-State Electrical Conductivity at a Metal-Insulator Transition On Silicon

Abstract

A quasi-one-dimensional metallic $\mathrm{S}\mathrm{i}(111)\mathrm{\text{\ensuremath{-}}}(4\ifmmode\times\else\texttimes\fi{}1)\mathrm{\text{\ensuremath{-}}}\mathrm{I}\mathrm{n}$ surface was investigated by a newly developed temperature-variable microscopic four-point probe method combined with in situ electron diffraction in ultrahigh vacuum. We have succeeded, for the first time, in detecting directly a surface metal-insulator transition around 130 K as a dramatic change of electrical conductivity through the surface states. An energy gap of $\ensuremath{\sim}300\text{ }\mathrm{m}\mathrm{e}\mathrm{V}$ at the low-temperature phase, influences of defects and phase locking between the neighboring charge-density-wave chains were elucidated from the temperature dependence of conductivity.