Interparticle coulombic decay in coupled quantum dots: Enhanced energy transfer via bridge assisted mechanisms

Abstract

Interparticle Coulombic Decay (ICD) is an efficient energy transfer process between two weakly interacting systems. ICD was recently proposed as the underlying fundamental mechanism for technological purposes based on quantum dot nanostructures, such as wavelength-sensitive detectors. Via ICD, an excited donor quantum dot releases its excess energy by ionizing a neighbouring acceptor dot. Here, we demonstrate that the presence of a third (ICD inactive) quantum dot can serve as a bridge between the two dots, which is shown to result in an enhancement of the efficiency of the ICD-mediated energy transfer. Furthermore, our results show that this enhancement is found to be robust against the change of the characteristics of the bridge quantum dot and particularly the depth and size. On the other hand, its relative position with respect to the donor and acceptor dots is found to foster the ICD when it is located in between the two dots. Our findings provide new insights for the development of ICD-based nanostructure technologies and particularly for rational design of three coupled quantum dots.

An Impurity Effect for the Rates of the Interparticle Coulombic Decay

“…at negative DM = −2.58 meV (−0.250 a.u.). This was just recently confirmed with an analytic rate equation including the superexchange term [20,23]. Here we encounter many cases with large distances (R > 150 nm) of which we know that tunneling is forbidden [9].…”

“…and(3), the depth of both QDs is identically D = 20.6 meV (2.0 a.u.). This is because their material is the same, namely GaAs, and they are attached to the same external voltage.Note that this is a difference to most of the works in the series on ICD in QDs originating from the first paper in 2011[9] and also to the work that models a similar three-QD system to what we propose here[23]. The QD widths are 2rL = 36.07 nm (3.33 a.u.)…”

“…In this way the ICD rate experiences a significant enhancement by a factor of five, when bringing the extra atom from a theoretically infinite distance closer into the center of the bond [20]. A similar investigation was done for ICD in QD pairs, in which superexchange ICD was found to play a crucial role in rate enhancement when being placed in between or next to the two QDs [23].…”

“…To distinguish such impurity effect from superexchange ICD, we are going to explore the effect both for large distances among the three centers and for the central potential being only very shallow. Superexchange ICD instead can only be operative at short distances among the two original atoms or QDs [20,21,22,23].…”

Three-electron dynamics of the interparticle Coulombic decay with two-dimensional continuum confinement

“…48 When being a somewhat deeper binding potential in short distance from the two partners undergoing ICD, the extra site, a QD of other geometry or material composition, supports superexchange ICD. 49 And when a full-depth binding potential is added, i.e. another QD of the same material as the others, it acts as a participator in a three-electron ICD process.…”