Impact of cation stoichiometry on the early stage of growth of SrTiO3 deposited by pulsed laser deposition

By performing in situ growth studies during pulsed laser deposition, we observed a strong reduction of the surface diffusion coefficients for slightly non-stoichiometric SrTiO3. Both, stoichiometric and non-stoichiometric thin films exhibit 2D layer by layer growth. However, in the non-stoichiometric case the 2D island coalescence is significantly delayed, which goes along with a shift of the reflection high electron energy diffraction (RHEED) minimum. We could explain this shift of the RHEED minimum by developing a model for the step density evolution taking into account finite surface diffusion.