Stress and Morphology Evolution during Island Growth

We performed a series of hybrid molecular-dynamics simulations of island growth on a substrate and monitored island stress evolution for several different island/substrate interfacial energies. Smaller (larger) interfacial energy yields islands with a stronger (weaker) compressive stress-thickness product. We present analytical results that suggest that the stress-thickness product is a linear function of the substrate coverage, with slope equal to minus the substrate surface stress, if the island is in mechanical equilibrium, and verify these results with simulation data.

Figure 1

The morphologies of islands grown with (a) strong, (b) intermediate, and (c) weak interfacial bonding. Dark and light gray atoms represent island and substrate atoms, respectively.

Figure 2

Stress-thickness product as a function of the number of atoms deposited. Each data point represents an average of the data obtained during the deposition of 40 adatoms (to minimize statistical fluctuations).

Figure 3

Stress thickness vs substrate surface coverage $\Theta$. The continuous curve is the best fit line. The slope of this line is $-18.8\pm 0.9\mathrm{GPa}\AA$.