Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 52: Quantum dots and wires: Optical properties IV

HL 52.1: Talk

Friday, March 31, 2006, 11:00–11:15, POT 151

Optical absorption and gain of Quantum Dots - Influence of Coulomb and carrier-phonon correlations — •Michael Lorke, Jan Seebeck, Torben R. Nielsen, Paul Gartner, and Frank Jahnke — Institute for Theoretical Physics, University of Bremen

In recent years, semiconductor quantum dots have been studied extensively due to possible applications in optoelectronic devices like LEDs or lasers. An important ingredient for the modeling of these devices as well as for practical applications is the knowledge of dephasing processes. They determine the homogeneous linewidth of the quantum dot resonances and limit the coherence properties of quantum dot lasers.

We use a microscopic theory to to study the optical absorption and gain properties of semiconductor quantum dot systems. The excitation-induced dephasing and the line-shifts of the quantum dot resonances are determined from a quantum kinetic treatment of correlation processes which includes non-Markovian effects due to Coulomb and carrier-phonon interaction. A special focus of these investigations is the clarification of the importance of various scattering channels due to the Coulomb interaction.

We observe a pronounced damping of the quantum dot resonances accompanied by strong line-shifts with increasing carrier density. Our results are compared to recent photoluminescence spectroscopy measurements of single QDs in which linewidths of several meV at room temperature are found.