In enrichment in (In,Ga)As/GaAs quantum dots studied by high-resolution x-ray diffraction and pole figure analysis

We report on an x-ray study of a 15X (InAs/InGaAs/GaAs) multiquantum dot st ack grown by metal organic chemical vapor deposition using high-resolution x-ray diffraction and pole figure analysis. No direct signal from the quant um dots is found by the high-resolution techniques. All rocking curves on d ifferent symmetric and asymmetric Bragg reflections can be simulated within the framework of dynamical theory assuming a perfect tetragonally distorte d InAs/InGaAs/GaAs multiquantum well system. The analysis of the diffuse sc attering intensity in the vicinity of the (113) reflection in the symmetric scattering geometry, however, reveals a signal from the quantum dots. The quantum dots consist of nearly pure InAs, whereas the mean In concentration in the wetting layer is only 43% indicating a strong In diffusion during t he Stranski-Krastanow formation process. (C) 1999 American Institute of Phy sics. [S0003-6951(99)02645-5].