Screening effects during late stage phase separation

Late stage phase separation is an important non-equilibrium thermodynamics process with a range of implications for applied systems such as thin film growth. A number of studies describe quantitatively Ostwald ripening, the d ominant process under mass conservation. In these models the concept of a s creening length occurs in different context, for three-dimensional systems to accommodate finite volume fractions of the minority phase, and for two-d imensional systems to circumvent the diverging steady state solution to the diffusion equation. We present a comprehensive review of this concept and show that the screening length in two- and three-dimensional systems has th e same form if the average cluster radius and the average cluster cluster d istance are used as parameters. In the experimental section, examples for t wo- and three-dimensional systems are given, showing that the screening len gth shields the interaction between clustering systems across a concentrati on step. This leads to sharper than expected interfaces between neighbourin g ripening systems on a surface, and explains the resistance of sub-surface silicide clusters to dissolve into a uniform, buried film during annealing . (C) 1998 Elsevier Science B.V. All rights reserved.