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

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