Si epitaxial growth on Br-Si(100):  How steric repulsive interactions influence overlayer development

Abstract

Scanning tunneling microscopy results show the consequences of Si adatom deposition onto Br-saturated Si͑100͒-͑2 ϫ 1͒. Those adatoms undergo an exchange reaction with Br and they are immobile at room temperature. In the low coverage regime, annealing to 650 K leads to dimerization, limited ordering, and the formation of short Si chains. Adatom capture by those chains produces features of even and odd numbers of atoms. Annealing at 700 K eliminates the odd chains, but diffusion is highly constrained by Br site blocking. With subsequent Si depositions, there is further nucleation of chains and chain growth. The local patterning of the Si chains reveals the influence of the Br steric repulsive interactions as out-of-phase structures were favored over in-phase structures around any given chain. Eventually, ͑3 ϫ 2͒ adlayer patches develop. Second layer chains appear after the deposition of ϳ0.3 ML, with layer-2 nucleation at antiphase domain boundaries. Bromine loss was observed, even at 650 K, and it is probably tied to the weaker bonding to single isolated Si adatoms.

Ab Initio Study of the Early Stage of Si Epitaxy on the Chlorinated Si(100) Surface

“…In other words, the adsorbed silicon atoms etch the chlorine layer but do not remove Si substrate atoms. The subsequent Si overgrowth on the substrate area free of Cl should lead to a more uniform growth of the epitaxial layers because of increased adatom mobility on Cl-free surface (e.g., Si adatom mobility is lower on Si(100)-2 × 1 surfaces terminated by hydrogen 11 and bromine 32 than on a clean surface). Note that the lowtemperature removal of Cl will not lead to the diffusion of dopants (e.g., P atoms) on the surface.…”