Elastic Misfit Strain Relaxation in Highly Strained InAs Dots on GaAs as Studied by Tem, AFM and VFF Atomistic Calculations

Abstract

The deposition of InAs on GaAs results, above a 1.75 monolayer coverage, in the formation of dots on a residual 2D wetting layer. Atomic force microscopy (AFM) measurements show that these dots are in the quantum size range (height 3 nm, half-base 12 nm). Transmission electron microcopy (AFM) observations show that they are coherently strained and the corresponding strain contrast is simulated using the dynamical electron diffraction contrast theory. The dot strain fields used for the TEM contrast simulations are either deduced from continuous elastic models or determined by valence force field (VFF) atomistic calculations. That experimental TEM images and simulated images should match shows that the methods of determination of the dot strain fields are valid.