A ReaxFF potential for Al-ZnO systems

A reactive field force potential has been created in order to model the structural effects of low percentage dopant aluminium in a zinc oxide (ZnO) system. The potential's parameters were fitted to configurations computed with density functional theory: binding energies were considered for surface structures and for Al in ZnO bulk crystals. Energies for Zn-Al alloys were also considered. Forces were fit to zero for all equilibrium structures and were also fitted for some non-equilibrium structures. As a first application of the model, the energetic deposition (0.1-40 eV) of an aluminium atom onto the polar surface of a ZnO (000 (1) over bar) is considered. For low energies the Al atom attaches to two preferred sites on the surface but as the energy increases above approximate to 15 eV subplantation is preferred at near normal incidence, with high diffusion barriers between stable sites. At these energies, reflection of the Al atom occurs at incident angles above approximate to 55 degrees.