Nanometer-scale sharpness in corner-overgrown heterostructures

A corner-overgrown GaAs∕AlGaAs heterostructure is investigated with transmission and scanning transmission electron microscopy, demonstrating self-limiting growth of an extremely sharp corner profile 3.5nm wide. In the AlGaAs layers, we observe self-ordered diagonal stripes, precipitating exactly at the corner, which show increased Al content measured with x-ray spectroscopy. A quantitative model for self-limited growth is adapted to the present case of faceted molecular beam epitaxial growth, and the corner sharpness is discussed in relation to quantum confined structures. We note that corner overgrowth maintains nanometer sharpness after microns of growth, allowing corner-shaped nanostructures.

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