Oscillating growth of surface roughness in multilayer films

Abstract

The surface and interface growth of binary multilayer films has been studied using nonlinear continuum theory. Numerical simulations show that the surface roughness of a multilayer film experiences an oscillating growth, with smoothing of the interface roughness existing at one type of interface and growth-induced roughening observed at another type of interface. Such interface smoothing and roughening effects are apparently related to the growth time of individual thin layers and consequently to the bilayer thickness. In particular, the change in the thickness ratio between adjacent layers shows a marked effect on the interface roughness. Our simulations also reveal that despite the existence of such an oscillating growth feature the surface roughness of a multilayer film almost exhibits an exponential dependence on the growth time and the scaling law found in the growth of single-layer films is also valid for multilayers.