Self-Assembly of
Concentric Quantum Double Rings

  Nano Lett., 5 (3), 425-428, 2005.

We demonstrate the self-assembled formation of concentric quantum double rings with high uniformity and excellent rotational symmetry using the droplet epitaxy technique. Varying the growth process conditions can control each ring's size. Photoluminescence spectra emitted from an individual quantum ring complex show peculiar quantized levels that are specified by the carriers' orbital trajectories.

Figure1:High-resolution scanning electron microscope image of the GaAs/Al_0.3Ga_0.7As concentric double rings.
Figure２: (a) PL of a single quantum concentric double ring structure (bottom) and the calculated energy shift with respect to the ground-state emission (top).
(b) Isosurface plots of the electronic probability density at 50% of the maxima in the concentric quantum double rings.