  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.
