Molecular dynamics study on low-energy sputtering properties of MgO surfaces

In an effort to understand microscopic processes occurring between MgO protective layers and impinging plasma ions in a discharge cell of plasma-display panel, sputtering properties of MgO(100) surface by He, Ne, and Xe atoms are studied with molecular dynamics simulations. Interatomic potentials between constituent atoms are fitted to first-principles data sets for representative configurations. Various incident directions of ions are considered with kinetic energies under 100eV. It is found that sputtering yields for the Ne atom are largest among tested noble gases. The angle dependence of sputtering yields indicates that (111)-oriented MgO films are much more vulnerable to ion attacks than (100)-oriented layers. A surface model including the monolayer step is also studied and it is found that the yields increase substantially for grazing-angle incidence.