Effect of strain on surface diffusion in semiconductor heteroepitaxy

[摘要] We present a first-principles analysis of the strain renormalization of the cation diffusivity on the GaAs(001) surface. For the example of In/GaAs(001)-c(4X4) it is shown that the binding of In is increased when the substrate lattice is expanded. The diffusion barrier DeltaE(epsilon) has a nonmonotonic strain dependence with a maximum at compressive strain values (epsilon <0), while being a decreasing function for any tensile strain ( >0) studied. We discuss the consequences of spatial variations of both the binding energy and the diffusion barrier of an adatom caused by the strain field around a heteroepitaxial island. For a simplified geometry, we evaluate the speed of growth of two coherently strained islands on the GaAs(001) surface and identify a growth regime where island sizes tend to equalize during growth due to the strain dependence of surface diffusion.

[关键词] FUNCTIONAL THEORY CALCULATIONS;STRANSKI-KRASTANOW GROWTH;POLY-ATOMIC SYSTEMS;ELECTRONIC-STRUCTURE;GAAS(001) SURFACE;QUANTUM DOTS;INAS;ISLANDS;ADATOM;STABILITY