Electronic properties of laser-annealed (111)-(1 × 1) surfaces of highly doped silicon

Highly degenerate As-doped $n$-type and B-doped $p$-type Si(111)-(1×1) surfaces have been prepared via ion implantation and laser annealing and studied using photoemission. For as concentrations of ∼4-7 at.%, surface states become very different from those for intrinsic Si(111)-(1×1), and the Fermi level $E_F$ at the surface moves to the conduction-band minima. For this "flat-band" Si surface, the deposition of Au results in a zero-height $n$-type Schottky barrier. Also, emission from the conduction-band minima has been directly viewed in momentum space.