Energetics and Kinetics of Self-Organized Structure Formation in Solution Growth – the SiGe/Si System

Abstract

When analyzing and modeling the self-organized structures and their evolution in misfit epitaxial growth, one encounters the problem of finding out whether the formation process is kinetically or energetically controlled. Generally the applied growth methods operate with rather high supersaturations just to ensure the appropriately high growth rate. The controlling step is in most cases the surface diffusion, for example in the physical or chemical vapor deposition methods. Thus, the resulting structure formation, though influenced by elastic energy reduction (elastic relaxation), is generally kinetically controlled. On the other hand, solution growth, i.e., liquid-phase epitaxy, while maintaining high deposition rates, deposits the epitaxial layer from a solvent that contains the respective solute in a small supersaturation generally maintained by a small undercooling. Such a small deviation from equilibrium and the high diffusivity of the solute in the liquid justifies solution growth to be considered energetic. One has to keep in mind, however, that the growth system, at any moment of growth, realizes the lowest energy configuration. The investigation of the evolution of the various self-organized structures in this case provides insight into the low-energy structures and helps to identify, by comparison to other growth experiments, kinetically influenced growth processes.