Coulomb interactions in single charged self-assembled quantum dots: Radiative lifetime and recombination energy

Dalgarno, P. A., Smith, J. M., McFarlane, J., Gerardot, B. D., Karrai, K., Badolato, A. , Petroff, P. M. and Warburton, R. J. (2008) Coulomb interactions in single charged self-assembled quantum dots: Radiative lifetime and recombination energy. Physical Review B, 77, 245311. (doi: 10.1103/PhysRevB.77.245311)

Abstract

We present results on the charge dependence of the radiative recombination lifetime, τ , and the emission energy of excitons confined to single self-assembled InGaAs quantum dots. There are significant dot-to-dot fluctuations in the lifetimes for a particular emission energy. To reach general conclusions, we present the statistical behavior by analyzing data recorded on a large number of individual quantum dots. Exciton charge is controlled with extremely high fidelity through an n -type field effect structure, which provides access to the neutral exciton ( X 0 ), the biexciton ( 2 X 0 ) , and the positively ( X 1 + ) and negatively ( X 1 − ) charged excitons. We find significant differences in the recombination lifetime of each exciton such that, on average, τ ( X 1 − ) / τ ( X 0 ) = 1.25 , τ ( X 1 + ) / τ ( X 0 ) = 1.58 , and τ ( 2 X 0 ) / τ ( X 0 ) = 0.65 . We attribute the change in lifetime to significant changes in the single particle hole wave function on charging the dot, an effect more pronounced on charging X 0 with a single hole than with a single electron. We verify this interpretation by recasting the experimental data on exciton energies in terms of Coulomb energies. We directly show that the electron-hole Coulomb energy is charge dependent, reducing in value by 5%–10% in the presence of an additional electron, and that the electron-electron and hole-hole Coulomb energies are almost equal.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Badolato, Professor Antonio
• Authors: Dalgarno, P. A., Smith, J. M., McFarlane, J., Gerardot, B. D., Karrai, K., Badolato, A., Petroff, P. M., and Warburton, R. J.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Physical Review B
• Publisher: American Physical Society
• ISSN: 1098-0121
• ISSN (Online): 1550-235X