Effects of wetting and misfit strain on the pattern formation of heteroepitaxially grown thin films

We investigate surface patterns of heteroepitaxially grown thin films using a three-dimensional kinetic Monte Carlo algorithm. Both the effects of elastic strain and wetting energy are taken into account. For the calculation of elastic strain energy induced by the lattice mismatch between the film and the substrate, a lattice discrete Green's function method is used and numerically evaluated. For the wetting effect, different function forms of wetting energy have been proposed to model the wetting intensity between thin film and the substrate materials. The effects of wetting and misfit strain together with other growth conditions such as deposition rate and temperature of the substrate are thus investigated. Three growth modes, i.e., Layer-By-Layer, Stranski-Krastanow (S-K), and Volmer-Weber (V-W) of thin films are demonstrated clearly in our investigations. The occurrence of S-K growth mode is affected by the competition between the wetting effect and the strain effect.