Stability of the surface of an elastically strained multicomponent film in a system with chemical reactions

The morphological stability of a flat elastically strained multicomponent film, the growth of which is controlled by the boundary kinetics, has been considered. It has been shown that the instability can be caused by fluctuations of mechanical stresses in the film, which affect the lifetime of adsorbents on the film surface. A stability criterion that relates the affinity of a chemical reaction on the surface to the stress in the film has been found. The growth of the GaN films on sapphire has been analyzed based on the obtained results. The influence of the flux ratio of Group III/V components on the morphology of the film has been investigated. It has been demonstrated that, in terms of this mechanism, smoother films are formed when their growth is controlled by nitrogen, whereas the characteristic roughness, which is comparable to the mean free path of adatoms, has developed when the growth is controlled by gallium.