title: Evidence of Quantum Resonance in Periodically-Ordered Three-Dimensional Superlattice of CdTe Quantum Dots.
abstract: Semiconductor quantum dot (QD) superlattices, which are periodically ordered three-dimensional (3D) array structures of QDs, are expected to exhibit novel photo-optical properties arising from the resonant interactions between adjacent QDs. Since the resonant interactions such as long-range dipole-dipole Coulomb coupling and short-range quantum resonance strongly depend on inter-QD nano space, precise control of the nano space is essential for physical understanding of the superlattice, which includes both of nano and bulk scales. Here, we study the pure quantum resonance in the 3D CdTe QD superlattice deposited by a layer-by-layer assembly of positively charged polyelectrolytes and negatively charged CdTe QDs. From XRD measurements, existence of the periodical ordering of QDs both in the lamination and in-plane directions, that is, the formation of the 3D periodic QD superlattice, was confirmed. The lowest excitation energy decreases exponentially with decreasing the nano space between the CdTe QD layers and also with decreasing the QD size, which is apparently indicative of the quantum resonance between the QDs rather than a dipole-dipole Coulomb coupling. The quantum resonance was also computationally demonstrated and rationalized by the orbital delocalization to neighboring CdTe QDs in the superlattice.
authors.affiliation: †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan.
authors.forename: DaeGwi
authors.initials: D
authors.lastname: Kim
authors.affiliation: †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Shougo
authors.initials: S
authors.lastname: Tomita
authors.affiliation: †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Ohshiro
authors.affiliation: †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Taichi
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: ‡Green Mobility Collaborative Research Center, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: Takenobu
authors.initials: T
authors.lastname: Sakai
authors.affiliation: §Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.|∥Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: I-Ya
authors.initials: IY
authors.lastname: Chang
authors.affiliation: §Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.|∥Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Kim
authors.initials: K
authors.lastname: Hyeon-Deuk
keywords: HOMO/LUMO delocalization; Quantum dot; density functional theory; quantum resonance; three-dimensional superlattice