▎ 摘　　要

By using first-principles calculation, we study adatom-vacancy pairs on graphenes. We found that the healing barrier of the adatom-vacancy pair is very small (0.06 eV) when the adatom is bonded to a nearest carbon atom of the mono-vacancy. Therefore, this pair is easily healed. On the contrary, when the adatom is located 4.26-5.54 angstrom far from the vacant site, the healing barrier becomes high (0.24-0.32 eV), but these barriers are lower than that of the adatom diffusion. It is therefore expected that these adatom-vacancy pairs are healed in low temperature range where the adatom does not diffuse. (C) 2012 The Japan Society of Applied Physics