Single Indium Atoms and Few-Atom Indium Clusters Anchored onto Graphene via Silicon Heteroatoms

Single atoms and few-atom nanoclusters are of high interest in catalysis and plasmonics, but pathways for their fabrication and placement remain scarce. We report here the self-assembly of room-temperature-stable single indium (In) atoms and few-atom In clusters (2-6 atoms) that are anchored to substitutional silicon (Si) impurity atoms in suspended monolayer graphene membranes. Using atomically resolved scanning transmission electron microscopy (STEM), we find that the symmetry of the In structures is critically determined by the three- or fourfold coordination of the Si anchors. All structures are produced without electron-beam induced materials modification. In turn, when activated by electron beam irradiation in the STEM, we observe in situ the formation, restructuring, and translation of the Si-anchored In structures. Our results on In-Si-graphene provide a materials system for controlled selfassembly and heteroatomic anchoring of single atoms and few-atom nanoclusters on graphene.

Automated summary

This research demonstrates the self-assembly of single indium atoms and few-atom indium clusters in suspended monolayer graphene membranes, anchored to substitutional silicon impurity atoms. Scanning transmission electron microscopy (STEM) revealed that the symmetry of the indium structures is dependent on the coordination of the silicon anchors. Furthermore, electron beam irradiation in STEM enables the observation of formation, restructuring, and translation of the silicon-anchored indium structures.