T. Tarkowski | Searcharxiv

arXiv2021

The structure of porous 2D boron crystals

In this work, we foresee the structure of a new class of borophenes with smaller 2D densities of atoms than those explored so far for 2D boron crystals. Boron atoms in the porous borophenes tend to be $5$-coordinated in contrast to commonly investigated structures with hexagonal holes for which the number of nearest neighbors of each atom varies from $3$ to $6$. High metallic character is the usual feature of borophenes, however, we have also identified a semimetallic borophene that turns into semiconductor upon unit cell expansion. A $10\%$ increase in lattice constant of this structure gives rise to an energy gap of $0.3\,\textnormal{eV}$. This extends to semiconductor industry the possible application of 2D boron crystals.

cond-mat.mtrl-sci↗

arXiv2016

Energy decomposition analysis of neutral and negatively charged borophenes

The effect of external static charging on borophenes - 2D boron crystals - is investigated by using first principles calculations. The influence of the excess negative charge on the stability of the 2D structures is examined using a very simple analysis of decomposition of the binding energy of a given boron layer into contributions coming from boron atoms that have different coordination numbers. This analysis is important to understand how the local neighbourhood of an atom influences the overall stability of the monolayer structure. The decomposition is done for the $\alpha$-sheet and its related family of structures. From this analysis, we have found a preference for 2D boron crystals with very small or very high charges per atom. The structures with intermediate charges are energetically not favourable. We have also found a clear preference in terms of binding energy for the experimentally seen $\gamma$-sheet and $\delta$-sheet structures that is almost independent on the considered excess of negative charge of the structures. On the other hand, we have shown that a model based solely on nearest-neighbour interactions, although instructive, is too simple to predict binding energies accurately.

cond-mat.mtrl-sci↗