  The effect of defects on the behavior of electrical conductivity in a
monolayer produced by the random sequential adsorption of linear $k$-mers
(particles occupying $k$ adjacent sites) onto a square lattice is studied by
means of a Monte Carlo simulation. The $k$-mers are deposited on the substrate
until a jamming state is reached, i.e. a state where no one additional particle
can be placed because the presented voids are too small or of inappropriate
shapes. The presence of defects in the lattice (impurities) and of defects in
the $k$-mers with concentrations of $d_l$ and $d_k$, respectively, is assumed.
The defects in the lattice are distributed randomly before deposition and these
lattice sites are forbidden for the deposition of $k$-mers. The defects on the
$k$-mers are distributed randomly. The sites filled with $k$-mers have high
electrical conductivity whereas the empty sites, and the sites filled by either
types of defect have a low electrical conductivity, i.e., a high-contrast is
assumed. We examined isotropic (both the possible orientations of a particle
are equiprobable) and anisotropic (all particles are aligned along one given
direction, $y$) deposition. To calculate the effective electrical conductivity,
the monolayer was presented as a random resistor network (RRN) and the
Frank--Lobb algorithm was used. The effects of the concentrations of defects
$d_l$ and $d_k$ on the electrical conductivity for the values of $k = 2^n$,
where $n =1,2,\dots, 5$, were studied. Increase of both the $d_l$ and $d_k$
parameters values resulted in decreases in the value of $\sigma$ and the
suppression of percolation. Moreover, for anisotropic deposition the electrical
conductivity along the $y$ direction was noticeably larger than in the
perpendicular direction, $x$. Phase diagrams in the ($d_l, d_k$)-plane for
different values of $k$ were obtained.
