  We study the optical and electrical properties of silver films with a graded
thickness obtained through metallic evaporation in vacuum on a tilted substrate
to evaluate their use as semitransparent electrical contacts. We measure their
ellipsometric coefficients, optical transmissions and electrical conductivity
for different widths, and we employ an efficient recursive method to calculate
their macroscopic dielectric function, their optical properties and their
microscopic electric fields. The topology of very thin films corresponds to
disconnected islands, while very wide films are simply connected. For
intermediate widths the film becomes semicontinuous, multiply connected, and
its microscopic electric field develops hotspots at optical resonances which
appear near the percolation threshold of the conducting phase, yielding large
ohmic losses that increase the absorptance above that of a corresponding
homogeneous film. Optimizing the thickness of the film to maximize its
transmittance above the percolation threshold of the conductive phase we
obtained a film with transmittance T = 0.41 and a sheet resistance
$R_{\square}^{\mathrm{max}}\approx2.7\Omega$. We also analyze the observed
emission frequency shift of porous silicon electroluminescent devices when Ag
films are used as solid electrical contacts in replacement of electrolytic
ones.
