Growth mechanisms of epitaxial metallic oxide SrRuO3 thin films studied by scanning tunneling microscopy

We report the deliberately controlled growth of epitaxial metallic oxide ${\mathrm{SrRuO}}_{\mathrm{3}}$ thin films in three distinctly different growth modes. Scanning tunneling microscopy and x-ray diffraction indicate that the growth mechanism for films on exact (001) ${\mathrm{SrTiO}}_{\mathrm{3}}$ substrates is two-dimensional nucleation, which results in a two domain in-plane structure. As the miscut angle of vicinal (001) ${\mathrm{SrTiO}}_{\mathrm{3}}$ substrates is increased, the growth mechanism changes to step flow which leads to single domain thin films. Films on (001) ${\mathrm{LaAlO}}_{\mathrm{3}}$ substrates have an incoherent three-dimensional island growth due to the large lattice mismatch, resulting in a bulk-like lattice. The vast difference in the growth mechanisms of these films leads to a corresponding difference in their electrical transport and magnetic behavior. Such nanoscale control of growth mechanism, surface morphology, and domain structure can be very important in the fabrication of novel perovskite oxide devices.