Mismatch and chemical composition analysis of vertical InxGa1−xAs quantum-dot arrays by transmission electron microscopy

Vertically stacked InxGa1−xAs/GaAs quantum dots have been fabricated by molecular beam epitaxy. Cross-sectional high resolution electron microscopy analyses demonstrate that the quantum dot size increases, and the interplanar spacings of {111} for quantum dots as well as the mismatch between the quantum dots and the spacer layers, is increased with the layer number. Chemical analysis shows that, as fabrication proceeds, indium content is increased and gallium content is decreased, leading to the changes of mismatch and interplanar spacing for the quantum dots.