Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 36: Optical properties

HL 36.11: Vortrag

Mittwoch, 29. März 2006, 18:45–19:00, POT 151

Radiative Lifetime of Excitons in Multi Quantum-Well Systems — •Martin Schäfer, Marco Werchner, Walter Hoyer, Mackillo Kira, and Stephan W. Koch — Department of Physics and Material Sciences Center, Philipps University, Marburg, Germany

Effects like superradiance occurring in multi-quantum-well systems suggest that the radiative coupling between the quantum-wells can change the exciton lifetime with respect to a single quantum well. Therefore, a fully quantum-mechanical theory [1,2] is applied to analyze the exciton lifetime in a planar array of multiple radiatively coupled quantum wells. In the incoherent limit, the exciton lifetime of optically active excitons is independent of the homogeneous dephasing and therefore determined by the radiative lifetime.

In this talk, it is shown that the exciton lifetime in a multi-quantum-well system is enhanced compared to that in a single quantum-well. The lifetime is determined by the specific coupling between the quantum-wells and thus influenced by their spacing as well as by the background refractive-index profile of the structure. In this connection, a step-function-like refractive-index profile is investigated where the distance of the first quantum-well to the step is shown to have strong influence on the exciton lifetime. Furthermore, it is shown that an exciton population in one quantum well is able to create exciton populations in neighboring quantum wells due to the radiative coupling.

[1] M. Kira, F. Jahnke, W. Hoyer and S.W. Koch, Prog. in Quantum Electron. 23, 189 (1999)

[2] M. Kira and S.W. Koch, E. Phys. J. D 36, 143 (2005)