Role of Transient Mobility on Submonolayer Island Growth: Extensions and Testing*

In studies of epitaxial growth a major goal is assessing the smallest stable cluster ($i+1$ monomers, with $i$ the critical nucleus size), by analyzing the capture zone distribution (CZD) or the scaling of incident flux $F$ to the density of stable islands $N$ ($N \propto F^\alpha$, with $\alpha$ the growth exponent). As noted in the previous talk, the GWD has well described the data in several experiments, including submonolayer para-hexaphenyl (6P) on amorphous mica (i $\approx$ 3). Different scaling ($F^\alpha$) for 6P at (small) large $F$ is attributed to (DLA) ALA dynamics, i.e. $i = (5) 7 \pm 2$.\footnote{L. Tumbek & A. Winkler, Surf. Sci. 606, L55 (2012)} Our recent theoretical work considered monomers propagating ballistically before thermalizing or attaching to islands, leading to scaling, non-monotonic crossover, and activation energies that account for the data and reconciling the values of $i$ \footnote{J. R. Morales-Cifuentes, T. L. Einstein, and A. Pimpinelli. Phys. Rev. Lett. 113, 246101 (2014)}. We present applications to other experimental systems: 6P on SiO$_2$ and pentacene (5A) on amorphous mica. We describe useful simplifying approximations, and preliminary kinetic Monte Carlo simulations including transient effects on growth.