Morphologies of epitaxial islands on a lattice-misfitted substrate

• 来源期刊: 中国物理B(英文版)
• 关键词: epitaxial island free energy equilibrium shape
• 年，卷（期）: 2008,（8）
• 页码范围: 3008-3013
• 页数: 6页
• 语种: 英文

摘要

Under certain growth conditions for systems with a film/substrate lattice misfit, the deposited material is known to aggregate into island-like shapes. We have obtained an analytical expression of the total free energy, which consists of strain energy, surface energy and intcrfacial energy of a coherent island/substrate system, and the change of equilibrium aspect ratio versus the volume of the island and the misfit of lattices in the system, which provides a broad perspectiveon island behaviour. These then were used to study the equilibrium shapes of the system. The results show that in order to minimize the total free energy, a coherent island will have a particular height-to-width aspect ratio, called equilibrium aspect ratio, that is a function of the island volume and misfit. The aspect ratio is increased with increasing islandvolume at a fixed misfit, and with increasing misfit strain between the island and substrate at a fixed island volume.Moreover, the effect of misfit dislocation on the equilibrium shape of the island is also examined. The results obtained are in good agreement with experiment of observations and thus can serve as a basis for interpreting the experiments.