  We study the surface growth generated by the random deposition of particles
of different sizes. A model is proposed where the particles are aggregated on
an initially flat surface, giving rise to a rough interface and a porous bulk.
By using Monte Carlo simulations, a surface has grown by adding particles of
different sizes, as well as identical particles on the substrate in (1 + 1)
dimensions. In the case of deposition of particles of different sizes, they are
selected from a Poisson distribution, where the particle's sizes may vary by
one order of magnitude. For the deposition of identical particles, only
particles which are larger than one lattice parameter of the substrate are
considered. We calculate the usual scaling exponents: the roughness, growth and
dynamic exponents $\alpha, \, \beta \,$ and $z$, respectively, as well as, the
porosity in the bulk, determining the porosity as a function of the particle
size. The results of our simulations show that the roughness evolves in time
following three different behaviors. The roughness in the initial times behaves
as in the random deposition model. At intermediate times, the surface roughness
grows slowly and finally, at long times, it enters into the saturation regime.
The bulk formed by depositing large particles reveals a porosity that increases
very fast at the initial times, and also reaches a saturation value. Excepting
the case where particles have the size of one lattice spacing, we always find
that the surface roughness and porosity reach limiting values at long times.
Surprisingly, we find that the scaling exponents are the same as those
predicted by the Villain-Lai-Das Sarma equation.
