ELASTIC STRAINS IN GAAS ALAS QUANTUM DOTS STUDIED BY HIGH-RESOLUTION X-RAY-DIFFRACTION/

We have studied a GaAs/AlAs quantum dot array using reciprocal space m apping around the (004) and (<(11) over bar3>) reciprocal lattice poin ts. Both the coherently and the diffusely scattered X-ray intensities were analysed by performing two-dimensional model calculations. From t he distribution of the diffracted intensities we deduced the average s train status in the dots. From the numerical simulations it is evident that random elastic strain fields are present, which extend through a lmost the whole volume of the quantum dot. The simulations of the X-ra y measurements revealed that the crystalline part of the dots is consi derably smaller as scanning electron micrographs would indicate, namel y 50 nm instead of 65 nm, respectively.