Anomalous scaling behavior in polymer thin film growth by vapor deposition

Abstract

As a first step towards understanding the anomalous kinetic roughening with multifractality found in recent experiments on vapor deposition polymerization (VDP) growth, we study a simple toy model of the VDP growth in a (1 + 1)- dimensional lattice, along with monomer diffusion, polymer nucleation, limited active end bonding, and shadowing effects. Using extensive numerical simulations, we observe that the global roughness exponent is different from the local one. It is argued that such anomalies in VDP growth are attributable to the instability induced by the non-local shadowing effects on active ends of polymers. Varying the ratio of the diffusion coefficient to the deposition rate by means of a cosine flux, we also consider the role of diffusion in kinetic roughening of polymer thin film growth, which is quite different from that for metal or semiconductor film growth. Finally, we suggest a ( 2 + 1)- dimensional version, which can be directly compared with experimental results.