Effects of ion beams on the early stages of MgO growth

Molecular dynamics simulations are performed to examine the effects of ion beams in selecting MgO island orientations during ion beam assisted deposition. Sputter yields are determined as a function of ion beam orientation for MgO islands of different sizes. While channeling does occur in small islands, the difference in sputter yields between channeling and nonchanneling orientations is much smaller in small islands than in larger islands or a continuous film. The ion beam is capable of disrupting the entire island structure at small island sizes, while channeling dependent sputtering occurs at larger island size. Since less sputtering occurs for channeling orientations, the ion beam produces an orientation-dependent island growth rate. This leads to island orientation-dependent nucleation rates. A new analytical model parameterized using the molecular dynamics sputter yield data is developed which predicts how growth conditions affect these island-orientation nucleation rates. Based upon these simulations and model results, we suggest a strategy to efficiently grow thin, highly textured MgO films.