Probing intermediates of the induction period prior to nucleation and growth of semiconductor quantum dots

The cradle of quantum dots

21 December 2017

Growing quantum dots in solution involves at least two previously unobserved stages before they begin to form.

Quantum dots are nanometre sized particles with tuneable electrical and optical properties. Their applications include solar energy conversion and biomedical imaging. A team including researchers from Sichuan University used ultraviolet absorption and X-ray scattering techniques to visualize cadmium (Cd) and telluride (Te) forming into CdTe quantum dots in a colourless liquid.

They observed CdTe monomers — molecules that can bind to form bigger molecules and eventually nanocrystals — and a range of ‘magic-sized clusters’ or molecular ensembles with a precise number of atoms that creates a stable structure. The observations support predictions of a multistage process for quantum dot nucleation, although how the magic-size clusters formed is yet to be resolved.

In addition, the team engineered three different magic-sized clusters, demonstrating the potential to improve control over the electronic and optical properties of quantum dots.

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References

1. Nature Communications 8, 15467 (2017). doi: 10.1038/ncomms15467