Transition from compact to porous films in deposition with temperature activated diffusion

We study a thin film growth model with temperature activated diffusion
of adsorbed particles, allowing for the formation of overhangs and pores, but
without detachment of adatoms or clusters from the deposit.
Simulations in one-dimensional substrates are performed for several values of
the diffusion-to-deposition ratio $R$ of adatoms with a single bond and of
the detachment probability $\epsilon$ per additional nearest neighbor (NN),
respectively with activation energies are $E_s$ and $E_b$.
If $R$ and $\epsilon$ independently vary, regimes of low and high porosity
are separated at $0.075\leq\epsilon_c\leq 0.09$,
with vanishingly small porosity below that point and finite porosity for larger
$\epsilon$.
Alternatively, for fixed values of $E_s$ and $E_b$ and varying temperature,
the porosity has a minimum at $T_c$, and a nontrivial regime in which it increases
with temperature is observed above that point.
This is related to the large mobility of adatoms, resembling features
of equilibrium surface roughening.
In this high-temperature region, the deposit has the structure of a critical percolation
cluster due to the non-desorption.
The pores are regions enclosed by blobs of the corresponding percolating backbone,
thus the distribution of pore size $s$ is expected to scale as $s^{-\tilde\tau}$ with
$\tilde\tau\approx 1.45$, in reasonable agreement with numerical estimates.
Roughening of the outer interface of the deposits suggests Villain-Lai-Das Sarma
scaling below the transition. Above the transition, the roughness exponent
$\alpha\approx 0.35$ is consistent with the percolation backbone structure via
the relation $\alpha = 2-d_B$, where $d_B$ is the backbone fractal dimension.