A bimodal size distribution of two-dimensional islands is inferred during interface formation in heteroepitaxial growth of bismuth ferrite on (001) oriented ${\mathrm{SrTiO}}_3$ by sputter deposition. Features observed by in situ x-ray scattering are explained by a model where coalescence of islands determines the growth kinetics with negligible surface diffusion on ${\mathrm{SrTiO}}_3$. Small clusters maintain a compact shape as they coalesce, while clusters beyond a critical size impinge to form large irregular connected islands and a population of smaller clusters forms in the spaces between the larger ones.

• Received 18 October 2013

DOI:https://doi.org/10.1103/PhysRevLett.112.075503