MORPHOLOGICAL STABILITY AND COMPOSITIONAL UNIFORMITY OF ALLOY THIN-FILMS

Alloy thin films differ from pure materials in two respects: the alloy components may be prone to phase separation and the lattice parameter of the film is generally a function of the alloy composition. Both of these characteristics affect the compositional uniformity of the film which has implications for the film's mechanical and opto-electronic properties. To explore these phenomena, we present a linear stability analysis of alloy film growth, which accounts for the stresses generat ed by both film-substrate misfit and compositional nonuniformities. We find that, when compositional stresses are considered an instability can be present and that this instability is generic to alloy crystal g rowth. This instability is due to the deposition process, along with c ompositionally generated stresses, and occurs even in the absence of a film-substrate misfit. We compare our predictions to other-related mo dels and to the experimental literature. (C) 1998 Elsevier Science B.V . All rights reserved.