Viable substrates for the honeycomb-borophene growth

Abstract

The two-dimensional honeycomb lattice is an important system for investigating exotic quantum physics. Boron, the neighboring element of carbon, may form a flat monolayer honeycomb lattice, namely the honeycomb-borophene ($h$-B), on the surface of specific materials. In this work, we evaluate the potential of eight fcc metal materials, including fcc Ge, Nb, Ta, Ag, Ti, W, Al, and Mo, as the possible substrate for epitaxial $h$-B growth through the first-principles calculations. We find that Al(111) is one of the good candidates, while other fcc(111) surfaces of Nb, Ta, Ti, W, and Mo are also very likely to serve as viable substrates to support the $h$-B growth, since their film-substrate binding energies are even larger than that on Al(111). It has been identified that there is a strong charge accumulation effect between $h$-B and the metal substrate to stabilize the plane $h$-B. Combining the analysis from the thermodynamical and the electronic aspects, it is likely that the fcc phase of the Ta and W, other than Al, can serve as the best substrates for $h$-B growth, owing to their large adhesive energy (${E}_{ad}$) and strong charge-transferring effect between $h$-B and substrate. However, it is nearly impossible to obtain a freestanding $h$-B for the same reason.