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

TL;DR

This study uses first-principles calculations to analyze how strain affects the binding and diffusion energies of Ge adatoms on Si and Ge surfaces, revealing significant changes that influence adatom behavior during growth.

Contribution

It provides the first detailed quantitative analysis of strain effects on Ge adatom diffusion and binding energies on Si and Ge surfaces using first-principles methods.

Findings

Binding energy increases by 0.21 eV per percent compressive strain.

Diffusion activation energy decreases by 0.12 eV per percent compressive strain.

Strain significantly alters adatom density and diffusivity at growth temperatures.

Abstract

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 eV and 0.12 eV per percent compressive strain. For a growth temperature of 600 degrees C, these strain-dependencies give rise to a 16-fold increase in adatom density and a 5-fold decrease in adatom diffusivity in the region of compressive strain surrounding a Ge island with a characteristic size of 10 nm.