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Open Access Nano Express

Impacts of Coulomb Interactions on the Magnetic Responses of Excitonic Complexes in Single Semiconductor Nanostructures

Wen-Hao Chang1*, Chia-Hsien Lin1, Ying-Jhe Fu2, Ta-Chun Lin2, Hsuan Lin1, Shuen-Jen Cheng1, Sheng-Di Lin2 and Chien-Ping Lee2

Author Affiliations

1 Department of Electrophysics, National Chiao Tung University, Hsinchu, 30010, Taiwan

2 Department of Electronics Engineering, National Chiao Tung University, Hsinchu, 30010, Taiwan

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Nanoscale Research Letters 2010, 5:680-685  doi:10.1007/s11671-010-9531-3

Published: 21 January 2010

Abstract

We report on the diamagnetic responses of different exciton complexes in single InAs/GaAs self-assembled quantum dots (QDs) and quantum rings (QRs). For QDs, the imbalanced magnetic responses of inter-particle Coulomb interactions play a crucial role in the diamagnetic shifts of excitons (X), biexcitons (XX), and positive trions (X). For negative trions (X) in QDs, anomalous magnetic responses are observed, which cannot be described by the conventional quadratic energy shift with the magnetic field. The anomalous behavior is attributed to the apparent change in the electron wave function extent after photon emission due to the strong Coulomb attraction by the hole in its initial state. In QRs, the diamagnetic responses of X and XX also show different behaviors. Unlike QDs, the diamagnetic shift of XX in QRs is considerably larger than that of X. The inherent structural asymmetry combined with the inter-particle Coulomb interactions makes the wave function distribution of XX very different from that of X in QRs. Our results suggest that the phase coherence of XX in QRs may survive from the wave function localization due to the structural asymmetry or imperfections.

Keywords:
Quantum dots; Quantum rings; Magnetophotoluminescence; Diamagnetic shift