The sputtering properties of artificial polymorphic AB binary compound crystals

Molecular dynamics (MD) simulations of the sputtering of artificial 1:1 binary compound targets, AB, are reported. The simulations explore the sensitivity of monomer and dimer sputter yields to AB target structure and interatomic potentials. The targets have the sphalerite, wurtzite and sodium chloride lattice structures, and their atomic and material properties resemble those of ZnS polymorphs. Two different sets of interatomic potentials were used for the simulations. In the symmetric model, all bonding interactions are equivalent, while in the asymmetric model, the A-B interactions are strengthened at the expense of the A-A and B-B interactions. Both models predict similar material properties for a given target. No systematic variations of sputter yields for individual targets can be discerned between the predictions based on the symmetric and asymmetric interaction models. The relative sputter yields of monomer species A and B are independent of target structure when the A and B atoms occupy surface sites of equivalent symmetry. The relative yields of the AA and BB dimer species are similarly insensitive to the target structure, but target-dependent variations of the relative yields of AB dimers are observed. Sputtering properties other than relative yields (e.g. clustering range, depth of origin) do show structure-dependent variations. In agreement with previous MD studies of sputtering from metals, the nearest-neighbour contribution to AB clusters is found to be typically ∼50%, and may be as low as 30%.