DFT calculations of energetic stability and geometry of O-terminated B- and N-doped diamond (1 1 1)-1 × 1 surfaces

J Phys Condens Matter. 2019 Jul 3;31(26):265002. doi: 10.1088/1361-648X/ab152f. Epub 2019 Apr 1.

Abstract

The non- and O-terminated diamond (1 1 1)-1 × 1 surfaces, with the substitutional B (or N) dopants in different atomic layers, have been modelled in the present study. The influences of the O adsorbates, dopant and dopant position on the adsorption energy, have been studied by performing the density functional theory (DFT) calculations. Various parameters were additionally calculated in order to analyze the obtained results: bond lengths, total electron densities, bond populations, atomic charges, Fukui functions (FFs) and density-of-states. Dangling bonds on non-terminated surfaces, O adsorbates, as well as dopants within various atomic layers were all found to induce local effects. In fact, the degree of influences of the dopant on the adsorption energy of the O adsorbates, as well as on parameters like the near-surface bond lengths, total electron density, bond populations and atomic charges, were all found to be dependent on the dopant position. More generally, the deeper the dopant position, the less influence it had on the surface structures and properties. The influences by the dopant in the 1st or 2nd C atomic layer were observed to be significant, but those in the 3rd to 5th C layers were almost negligible. It was also found that the B dopant would decrease the adsorption energy of the adjacent O adsorbates, while the N dopant in the 2nd layer would increase it. Furthermore, the combination of the O adsorbates, together with the dopants within the 1st or 2nd C layer, could induce significant elongation of the bonds between neighboring atoms within the 1st and 2nd layers (i.e. C-C, C-B or C-N bonds). Moreover, all the terminating O atoms could react strongly with either the electrophilic or the nucleophilic species.