Structure of Bi-dimer linear chains on a Si(100) surface: A scanning tunneling microscopy study

The structure of bismuth-induced Si(100) surfaces has been investigated by scanning tunneling microscopy (STM). Bismuth atoms that adsorb on the surfa ce at 480 degrees C form long linear belts in the Si(100) topmost layer. Ea ch belt consists of two chains of bismuth dimers, and stretches parallel to the x2 direction of the terrace of the clean Si(100)(2 x 1) surface. From the STM images taken after hydrogen adsorption on the surface, we found tha t the linear chains of bismuth dimers substitute for four Si-dimer rows on the terrace. We proposed a structural model for the bismuth-dimer chains.