Analysis of a combined influence of substrate wetting and surface electromigration on a thin film stability and dynamical morphologies

TL;DR

This paper develops a PDE-based model to analyze how substrate wetting and surface electromigration jointly affect the stability and morphology evolution of ultrathin solid films, revealing stability domains and nonlinear behaviors.

Contribution

It introduces a combined model incorporating surface electromigration and wetting effects, with anisotropic adatom mobility, for the first time in analyzing film stability and morphology.

Findings

Identifies parameter domains of instability for wetting and non-wetting films.

Discovers nonlinear steady-state solutions under certain conditions.

Observes coarsening behavior in strongly wetting films.

Abstract

A PDE-based model combining surface electromigration and wetting is developed for the analysis of morphological stability of ultrathin solid films. Adatom mobility is assumed anisotropic, and two directions of the electric field (parallel and perpendicular to the surface) are discussed and contrasted. Linear stability analyses of small-slope evolution equations are performed, followed by computations of fully nonlinear parametric evolution equations that permit surface overhangs. The results reveal parameter domains of instability for wetting and non-wetting films and variable electric field strength, nonlinear steady-state solutions in certain cases, and interesting coarsening behavior for strongly wetting films.