Molecular dynamics simulation of metal oxide growth on SiTiO₃

Thin films of strontium titanate, as well as its component oxides, have been of great interest due to their applicability in electronic devices. In this manuscript we review our work to examine the growth of SrO, TiO₂, and SrTiO₃ (STO) thin films on STO using classical molecular dynamics simulations. In particular, the simulations considered the deposition of SrO and TiO₂ molecules and stoichiometric STO clusters at incident energies of 0.1, 0.5, and 1.0 eV/atom onto the (001) surface of STO. The role of surface termination layer (SrO vs. TiO₂), incident energy, and incident particle size and deposition scheme in the case of STO deposition were investigated. In the case of SrO deposition, smooth, ordered films were produced at all incident energies considered and for both surface terminations. In contrast, in the case of TiO₂ deposition, three-dimensional islands were formed under all the conditions considered. The predicted growth modes were shown to be a consequence of the mobility and interaction energy of each particle (SrO or TiO₂) with the surface. In the case of STO thin film growth three deposition schemes were explored: (i) alternating particle deposition (APD), (ii) alternating monolayer deposition (AMD), and (iii) cluster deposition. For APD, a beam of alternating SrO and TiO₂ molecules was deposited on the (001) surface of STO with incident kinetic energies of 0.1, 0.5 or 1.0 eV/atom. AMD consisted of the deposition of alternating monolayers of pure SrO and TiO₂, where both had incident energies of 1.0 eV/atom. SrTiO₃ cluster deposition considered the deposition of 1, 2, 3, and 4-unit STO stoichiometric clusters with incident energies of 1.0 eV/atom. On the whole, some layer-by-layer growth was predicted to occur on both SrO- and TiO₂-terminated STO for each type of deposition scheme.