Nucleation and growth of primary nanostructures in SrTiO(3) homoepitaxy

SrTiO(3) nanoislands on SrTiO(3) (001) in a diffusion-limited growth regime were studied using in situ scanning tunneling microscopy (STM). The STM images revealed two characteristic features of nucleation stages. First, the minimum lateral size of the one-unit-cell (uc)-high SrTiO(3) islands was 4 × 4 uc(2). Second, one-dimensional SrTiO(3) islands of a 4 uc width grew along the crystal symmetry directions. These observations suggest that 4 × 4-uc(2) islands act as a minimum nucleation seed, and the addition of SrTiO(3) molecular species of the same width is the primary and dominant growth process in SrTiO(3) homoepitaxy. A close inspection of the surface of the substrate during the deposition process revealed possible connections between surface reconstruction and energetically favorable nucleation of SrTiO(3) islands.