TRANSMISSION-ELECTRON MICROSCOPY STUDY OF THE SHAPE OF BURIED INXGA1-XAS GAAS QUANTUM DOTS/

High-resolution electron microscopy, on-zone bright-field imaging, and image simulation were used to investigate the shape of capped In0.06G a0.4As/GaAs semiconductor quantum dots. Cross-section [110] high-resol ution images suggest that the quantum dots are lens shaped, while the [001] on-zone bright-field images show a contrast that suggests a quan tum dot morphology with four edges parallel to [100]. The image simula tion, however, suggests that a spherical quantum dot can produce a squ are-shaped image. These observations lead to the conclusion that the q uantum dots in buried In0.6Ga0.4As/GaAs semiconductor heterostructures are lens shaped.