Nature Communications – Precise engineering of quantum dot array coupling through their barrier widths

Researchers from CFM Donostia, in collaboration with international partners, have tuned the confinement and coupling properties of quantum dots by precise engineering of the barrier width existing between the pores of organic networks. These confining structures (analogous to artificial atoms) change their separation by selective exchange of a single atom in their haloaromatic precursors, similar to the butterfly effect.

The report of these results has been published this week in Nature Communications and provide a fundamental understanding of concepts that bear the prospect of being key for future molecular devices and quantum computation.

Quantum dots (QDs) are analogous to artificial atoms, as they confine electrons with discrete energy levels. They can aggregate to form QD solids whose final properties are based on their cooperative interaction, suitable for many technological applications. Ideal QD solids demand truly monodisperse building blocks to prevent undesirable anomalies. However, so far, the real ones exhibit significant structural variations. Digital structural fidelity is achieved on surfaces through atom-by-atom and molecular manipulation or by self-assembled molecular nanoporous networks. Control of the potential barriers between neighbour QDs is essential to alter the crosstalk (coupling) between the existing units and also to engineer two dimensional electron gases (2DEG). Here^(*), researchers at the CFM, in collaboration with international partners, show that precise engineering of the barrier width can be experimentally achieved by a single atom substitution (sulfur vs. oxygen) in a haloaromatic compound. As a result, the electron confinement is tuned in such a way that it affects the degree of QD intercoupling. This work not only complements the toolbox for tuning surface electronic properties, which started in the 90’s with the quantum corrals, but it is also prone to help in deriving clear conceptual ideas on QD coupling, which is an essential parameter for next-generation computing or device technologies.

Figure. Self-assembly generates perfectly ordered arrays of quantum dots. These confine electrons within them while still allowing crosstalk (coupling), which are tuned through their barrier width.