Surface islands and their elastic interaction with adatoms

We describe the elastic interaction between adatoms on a (001) bcc surface and monolayer-high two- and three-dimensional islands, within the general c ontext of thin-film growth. A discrete harmonic model based on the concepts of eigenstrain and surface stress yields the elastic field owing to the pr esence of adatoms and islands. Adatoms can be attracted or repelled by isla nds, depending on the sign of the interaction energy. Our results indicate that the elastic field does not generally favor a flat two-dimensional grow th mode for homoepitaxy, or heteroepitaxy, when the overlayer is in compres sion. Based on elastic interactions alone, our results indicate that, in he teroepitaxy, two-dimensional step-flow growth becomes likely only for overl ayers in tension. The model used in the study offers substantial advantages in computational efficiency when compared with atomic simulations that are the norm in this field. (C) 2000 Elsevier Science B.V. All rights reserved .