Bi on Si(111): Two phases of the √3 × √3 surface reconstruction

Abstract

Scanning tunneling microscopy (STM) has been used to determine the surface structure of the \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 reconstruction induced by Bi on the Si(111) surface. The STM images show that there are two distinct ordered surfaces with \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 periodicity. At 1/3-monolayer Bi coverage, the \ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 phase consists of one Bi adatom per unit cell adsorbed at ${\mathit{T}}_{4}$ sites on a Si(111) bilayer. At nearly one monolayer of Bi coverage, STM images show protrusions with a complex shape dependent on bias voltage. These STM images are discussed and compared with structural models derived from previous experimental studies.