Coarsening Dynamics of Crystalline Thin Films

TL;DR

This paper investigates the coarsening dynamics of crystalline thin films, revealing anisotropic scaling on quadratic substrates with a typical exponent near 0.236, and isotropic growth with an exponent of 1/3 on triangular substrates.

Contribution

It provides analytical and numerical analysis of coarsening exponents and scaling behaviors for different substrate symmetries in thin-film growth.

Findings

Coarsening on quadratic substrates exhibits anisotropic scaling with a typical exponent ~0.236.

Growth on triangular substrates is characterized by a single length scale with an exponent of 1/3.

The coarsening exponent varies between 0 and 1/3 depending on material parameters.

Abstract

The formation of pyramid-like structures in thin-film growth on substrates with a quadratic symmetry, e.g., {001} surfaces, is shown to exhibit anisotropic scaling as there exist two length scales with different time dependences. Analytical and numerical results indicate that for most realizations coarsening of mounds is described by an exponent n=0.2357. However, depending on material parameters, n may lie between 0 (logarithmic coarsening) and 1/3. In contrast, growth on substrates with triangular symmetries ({111} surfaces) is dominated by a single length scale and an exponent n=1/3.