Chemical and strain effects on Boron-doped Si(100)

Theoretical investigations uncover complex strain-induced modes of boron or dering at the Si(100) surface, which are highly anomalous in comparison wit h other group III impurities. The fundamental units of the clustering proce ss are subsurface pairs of B atoms. The structural relaxations around segre gated B impurities are substantial and the induced strain fields couple wit h the (2x1) dimer reconstruction of the surface to stabilize complex, zigza g modes of ordering. Impurity configurations exist that are strongly bound with respect to isolated subsurface impurity pairs up to the critical dopin g level of 0.5 monolayer. Above this doping level, however, all modes of or dering of the impurities at the surface are repulsive. A number of experime ntal observations are explained and interesting structures are predicted. [ S0163-1829(99)07207-0].