First-principles calculation of the effect of strain on the diffusion of Ge adatoms on Si and Ge(001) surfaces

[摘要] First-principles calculations are used to calculate the strain dependencies of the binding and diffusion-activation energies for Ge adatoms on both Si(001) and Ge(001) surfaces. Our calculations reveal that the binding and activation energies on a strained Ge(001) surface increase and decrease, respectively, by 0.21 and 0.12 eV per percent compressive strain. For a growth temperature of 600 degreesC, these strain-dependencies give rise to a 16-fold increase in adatom density and a fivefold decrease in adatom diffusivity in the region of compressive strain surrounding a Ge island with a characteristic size of 10 nm.

[关键词] INITIO TOTAL-ENERGY;AB-INITIO;SHAPE TRANSITION;EPITAXIAL-GROWTH;NANOCRYSTALS;ADSORPTION;MORPHOLOGY;EVOLUTION;PYRAMIDS;ISLANDS