Dynamic scaling study of vapor deposition polymerization: A Monte Carlo approach

Abstract

The morphological scaling properties of linear polymer films grown by vapor deposition polymerization are studied by 1+1D Monte Carlo simulations. The model implements the basic processes of random angle ballistic deposition (F) , free-monomer diffusion (D) and monomer adsorption along with the dynamical processes of polymer chain initiation, extension, and merger. The ratio G=D/F is found to have a strong influence on the polymer film morphology. Spatial and temporal behavior of kinetic roughening has been extensively studied using finite-length scaling and height-height correlations H(r,t). The scaling analysis has been performed within the no-overhang approximation and the scaling behaviors at local and global length scales were found to be very different. The global and local scaling exponents for morphological evolution have been evaluated for varying free-monomer diffusion by growing the films at G=10 , 10(2), 10(3), and 10(4) and fixing the deposition flux F. With an increase in G from 10 to 10(4), the average growth exponent beta approximately 0.50 was found to be invariant, whereas the global roughness exponent alpha(g) decreased from 0.87 (1) to 0.73 (1) along with a corresponding decrease in the global dynamic exponent z(g) from 1.71(1) to 1.38(2). The global scaling exponents were observed to follow the dynamic scaling hypothesis, z(g)=alpha(g)/beta. With a similar increase in G however, the average local roughness exponent alpha(l) remained close to 0.46 and the anomalous growth exponent beta(*) decreased from 0.23(4) to 0.18(8). The interfaces display anomalous scaling and multiscaling in the relevant height-height correlations. The variation in H(r,t) with deposition time t indicates nonstationary growth. A comparison has been made between the simulational findings and the experiments wherever applicable.

Growth of SiO2 and TiO2 thin films deposited by reactive magnetron sputtering and PECVD by the incorporation of non‐directional deposition fluxes

“…Monte Carlo (MC) models are widely used for the simulation of the growth of thin films 27–29, and the one we use in this paper has already been successfully applied in many cases 16, 17, 19. It considers the deposition of effective particles on a cubic three‐dimensional N L × N L × N H grid, each cell representing a spatial volume of Δ 3 , with periodic boundary conditions, whose cells may take the values 0 (empty cell), or 1 (a deposited particle occupies the cell).…”

Role of diffusion in scaling of polymer chain aggregates found in vapor deposition polymerization

“…A 1 + 1D lattice model similar to the one employed earlier [15,17,18] was used in our study of polymer chain aggregates. In our computational model, a number of Monte Carlo moves were employed to simulate various dynamical processes occurring during the VDP growth.…”

“…Although vapor transfer [11][12][13][14] is a popular method used to grow organic nanostructures, literature on the size controllable growth of the nanostructures is very limited. Many recent studies [15][16][17][18][19] have focused on the behavior of overall polymer films properties like film density, interface width, end-to-end distance, etc. However, there is a very limited understanding of the aggregation process of polymer chains themselves apart from literature on submonolayer studies of VDP [16] that reported the existence of three distinct growth regimes: initiation (I), chain propagation (P ), and saturation regime (S) and the recent experimental work on island nucleation during VDP [20] that indicates a new type of surface growth governed by reaction-limited aggregation in the films grown by VDP.…”