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

TL;DR

This study uses first-principles calculations to explore how substrate effects influence the structure and electronic properties of bismuth adsorbed on graphene, revealing stable configurations and electronic features consistent with experiments.

Contribution

It provides a detailed theoretical analysis of substrate-induced structures and electronic properties of Bi-adsorbed graphene, including the effects of temperature and substrate interactions.

Findings

Hexagonal Bi arrangements are substrate-dominated.

Temperature can induce nanocluster formation.

Electronic density of states matches experimental tunneling data.

Abstract

The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a $\sim 50$ meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value 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.