Homoepitaxial growth kinetics in the presence of a Schwoebel barrier

Abstract

Nowadays it is well-recognized that the additional barrier to downhill adatom diffusion at the step edge plays an important role in the epitaxial growth. Very recently we have developed a simple model for homoepitaxial layer growth kinetics which allows to take into account the Schwoebel barrier impact on adatoms interlayer diffusion by using the concept of a feeding zone, as we have proposed earlier. This paper is devoted to further refinement and extension of the model to the cases of an arbitrary nucleus size and coalescence behaviour of growing islands. The model consists of an infinite set of coupled non-linear rate equations for adatom and 2D island surface densities and coverage in each successive growing layer. These equations in combination with an integral condition determining the new layer formation onset fully describe homoepitaxial growth kinetics at predetermined five model parameters, characterizing adatoms diffusion rate, critical nucleus size and stability, Schwoebel barrier effect, and coalescence. The growth mechanisms and kinetics in a wide range of parameter values are studied and growth mechanism phase diagrams in various parameter spaces are constructed and discussed.