Geometrical vs. statistical models for describing phase transition kinetics in thin films

Abstract

We present calculations and simulations to investigate different theories describing phase transitions in thin films, with special emphasis on the growth of the new phase after nucleation. In particular, models with geometric and statistical growth rules are compared. It is demonstrated that the commonly employed geometrical approach, which assumes nucleation and subsequent radial growth of the newly formed phase, has distinct limitations for thin film systems. More realistic statistical Monte Carlo simulations that are governed by statistical growth rules, predict that a non-spherical (prolate) shape may develop after nucleation at or near a surface or interface. In addition, the predicted kinetics of the phase transformation is notably different for the geometric vs. the statistical model, for similar parameters. The simulation results are compared to recent experiments on the crystallization of thin amorphous solid water films.