Substrate-induced structures of bismuth adsorption on graphene: a first principle study

摘要

The geometric and electronic properties of Bi-adsorbed monolayer graphene,enriched by the strong effect of substrate, are investigated byfirst-principles calculations. The six-layered substrate, corrugated bufferlayer, and slightly deformed monolayer graphene are all simulated. Adatomarrangements are thoroughly studied by analyzing the ground-state energies,bismuth adsorption energies, and Bi-Bi interaction energies of different adatomheights, inter-adatom distance, adsorption sites, and hexagonal positions. Ahexagonal array of Bi atoms is dominated by the interactions between the bufferlayer and the monolayer graphene. An increase in temperature can overcome a$\sim 50$ meV energy barrier and induce triangular and rectangularnanoclusters. The most stable and metastable structures agree with the scanningtunneling microscopy measurements. The density of states exhibits a finitevalue at the Fermi level, a dip at $\sim -0.2$ eV, and a peak at $\sim -0.6$eV, as observed in the experimental measurements of the tunneling conductance.