Adsorption and migration of selenium atoms on a hydrogen-terminated diamond (001) surface: A first-principles study

To study the possibility of the use of Se-doped diamond films for biomaterial applications, first-principles calculations have been performed to evaluate the adsorption and migration of selenium (Se) atoms on a hydrogen-terminated diamond [H-Ter-D] (0 0 1) surface. The calculation results indicate that while a selenium atom generally cannot be stably adsorbed on the surface, it can bond to a surface carbon atom on the surface with one open radical site (1ORS), with an adsorption energy of 2.74 eV. Moreover, selenium atoms can combine with two surface C atoms, with adsorption energies from 4.10 eV to 4.67 eV. The migration activation energy of the selenium atoms on the surface is approximately 1.34 eV. A density of states examination presents an interesting result. On the surface of the 2ORS slabs, after bonding with two surface C atoms, the selenium atom no longer has any unpaired electrons, and its magnetic moment becomes 0 mu(B). In this case, a deposited carbon atom can combine with the selenium atom by a triple bond, and then the C-Se molecule is desorbed from the surface. This outcome implies that the direct selenium doping method can only fabricate Se-doped diamond films with very low selenium incorporation.