Atomically Resolved Structure and Bonding of Delta-Doped Boron Layers on Si(001).

摘要

Scanning tunneling microscopy has been used to study the formation of delta-doped layers by thermal decomposition of diborane on Si(001). STM images reveal a number of boron-induced reconstructions which arise from ordered arrangements of three structural subunits. Based on the symmetry of the STM images and the bonding locations of the observed features with respect to the Si(001) lattice, a structural model is proposed with accounts for the observed STM features. The principal structural subunit is shown to be an ordered arrangement of four boron atoms at substitutional sites in the first bulk-like silicon layer, which is then capped with ordered arrangements of silicon dimers and dimer vacancies.