Atomic force microscopy examination of the evolution of the surface morphology of Bi 4Ti 3O 12 grown by molecular beam epitaxy

Abstract

The surface morphology of (001) Bi 4Ti 3O 12 grown on (001) SrTiO 3 by reactive molecular beam epitaxy (MBE) has been examined using atomic force microscopy (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 transition to 3-dimensional growth occurs, leading to well-defined mounds. This implies a Stranski–Krastonov growth mode. During growth, the morphology follows a behavior consistent with the dynamic scaling hypothesis and we extract values for the scaling exponents α and β from the AFM data. A thickness variation in α is observed and reflects the strain relief associated with the Stranski–Krastonov growth.