Atomic Models, Domain-Wall Arrangement, And Electronic Structure Of The Dense Pb/Si(111)-Root 3x Root 3 Phase

Despite extensive work in the literature, the structure of the dense Si(111)-Pb(root3 x root3) phase (ideal coverage theta = 4/3 ML) is still unknown because a variety of phases can form, within few percent coverage variation. These phases differ in the way equivalent root3 x root3 domains self-organize in different patterns with different domain-wall arrangements. With scanning tunneling microscopy and first-principles calculations we have identified the atomic structure within domains, domain-wall arrangement, and the binding site (H3 or T4) occupied by Pb atoms within each domain.