A Self-Directed Growth Process for Creating Covalently Bonded Molecular Assemblies on the H−Si(100)-3×1 Surface

A chain reaction initiated at a dangling bond on a H-terminated Si(100)-3×1 surface leads to the creation of contiguous, linear multimolecular assemblies. In contrast to a similar growth process observed on the H−Si(100)-2×1 surface, the linear structures grow in the cross-row direction, rather than parallel to dimer rows. This process is enabled by both an uncommonly high rate of H atom diffusion, specifically in the cross-row direction, and a low barrier to H atom abstraction from dihydride sites. These results demonstrate that anisotropy inherent to the substrate can be imposed upon molecular assemblies formed via this “self-directed” growth process.