Electronic states due to surface doping: Si(111)√3×√3B

A {}3 ×{} {}3 surface reconstruction is obtained on Si(111) when B diffuses from the bulk to the surface in heavily doped Si samples. First-principles total-energy calculations show that the lowest-energy atomic configuration for this reconstruction consists of a B atom at a subsurface substitutional site, directly underneath a Si adatom. Surface electronic states observed by photoemission and inverse photoemission experiments are analyzed through electronic structure calculations and shown to be related to the back-bond and the dangling-bond states of the Si adatom.