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

被引:75
作者
Dalgarno, Paul A. [1 ]
Smith, Jason M. [1 ,2 ]
McFarlane, Jamie [1 ]
Gerardot, Brian D. [1 ]
Karrai, Kahled [3 ]
Badolato, Antonio [4 ]
Petroff, Pierre M. [4 ]
Warburton, Richard J. [1 ]
机构
[1] Heriot Watt Univ, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Midlothian, Scotland
[2] Univ Oxford, Dept Mat, Oxford OX1 3PH, England
[3] Ctr NanoSci, Dept Phys LMU, D-80539 Munich, Germany
[4] Univ Calif Santa Barbara, Dept Mat, Santa Barbara, CA 93106 USA
关键词
D O I
10.1103/PhysRevB.77.245311
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We present results on the charge dependence of the radiative recombination lifetime, tau, 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 (2X(0)), and the positively (X1+) and negatively (X1-) charged excitons. We find significant differences in the recombination lifetime of each exciton such that, on average, tau(X1-)/tau(X-0)=1.25, tau(X1+)/tau(X-0)=1.58, and tau(2X(0))/tau(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.
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页数:8
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