Atomic force microscopy examination of the evolution of the surface morphology of Bi4Ti3O12 grown by molecular beam epitaxy

The surface morphology of (0 0 1) Bi4Ti3O12 grown on (0 0 1) SrTiO3 by reac tive molecular beam epitaxy (MBE) has been examined using atomic force micr oscopy (AFM). Initial nucleation of a 1/4 unit cell thick layer is followed by growth of 1/2 unit cell thick layers. Between 9 and 16 layers, a transi tion to 3-dimensional growth occurs, leading to well-defined mounds. This i mplies a Stranski-Krastonov growth mode. During growth, the morphology foll ows a behavior consistent with the dynamic scaling hypothesis and we extrac t values for the scaling exponents alpha and beta from the AFM data. A thic kness variation in alpha is observed and reflects the strain relief associa ted with the Stranski-Krastonov growth.