Kinetic Roughening in Polymer Thin Film Growth

Kinetic roughening is revisited in the context of polymer thin film growth by vapor deposition using the simplest toy model of chemical vapor deposition polymerization (CVDP) growth, which was employed in [J. Stat. Mech. (2009) P02031]. As the ratio of monomer di_usion rate D to the deposition flux F of monomers (G = D=F) increases, dynamic scaling of the CVDP growth is investigated in (1+1) and (2+1) dimensions. Measuring the surface width (height fluctuations) and the q-th order moments of height-height correlation function, it is observed that anomalous scaling behavior and multifractality exist. In order to speculate the origin of such anomalies, the following two scenarios are suggested and tested: One is that the cosine flux of incident monomers (random angle deposition) is essential in anomalous kinetic roughening phenomena and the other is that the multi-a_ne structure of CVDP growing surfaces is attributed to the non-local shadowing e_ect caused by the cosine flux of incident monomers, which yields the power-law distribution of steps. Based on the comparison of the ballistic deposition model with some modification of noise, namely the power-law distribution of noise, it is numerically confirmed that two scenarios turn to be true. This implies that dynamic scaling of the CVDP growth depends not only on what value is used for the ratio of monomer di_usion rate to deposition flux (G) but also on what kind of intrinsic and extrinsic noise exists.