Initial stages of chain formation in a single layer of (In,Ga)As quantum dots grown on GaAs (100)

The self-organized formation of In0.40Ga0.60As quantum dot chains was investigated using x-ray scattering. Two samples were compared grown on GaAs(100) by molecular beam epitaxy. The first sample with a single layer of In0.40Ga0.60As dots shows weak quantum dot alignment and a corresponding elongated shape along [01¯1], while the top layer of a multilayered In0.40Ga0.60As∕GaAs sample exhibits extended and highly regular quantum dot chains oriented along [01¯1]. Numerical calculations of the three-dimensional strain fields are used to explain the initial stages of chain formation by anisotropic strain relaxation induced by the elongated dot shape.