Modelling thin film growth in the Ag–Ti system

Abstract

Simulations of thin film growth in the Ag–Ti system are presented using molecular dynamics combined with an adaptive kinetic Monte Carlo method (AKMC) with a modified embedded atom potential fit to ab initio data for the surface energies. For the model, atoms are assumed to deposit normally with a kinetic energy of 1–3 eV, with a typical deposition rate of around 10 monolayers per second, similar to what might be expected in a sputter deposition process. For the growth of Ti on the Ag (100) and Ag (111) surfaces, the Ti adatoms prefer to exchange with the original surface layer atoms creating a mixed Ag/Ti surface. On a silver substrate, up to four mixed layers need to be formed before a pure Ti layer is obtained. Conversely, simulations of Ag depositing onto Ti (0001) showed that in the initial phase of growth, the Ag adatoms prefer to be separated before a complete first layer of Ag was obtained in a close-packed structure. The implementation of a super-basin method within AKMC allowed the simulation of 0.4s of Ti growth on the Ag substrates, with up to 3 new layers added.