Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 21: Quantum Dots and Wires, Optical Properties I: Nitrides

HL 21.1: Vortrag

Dienstag, 23. März 2010, 09:30–09:45, H17

Theory for Optical Properties of Nitride-based Quantum Dot Systems — •Kolja Schuh, Michael Lorke, Jan Seebeck, Stefan Schulz, Paul Gartner, Gerd Czycholl, and Frank Jahnke — Institute for Theoretical Physics, University of Bremen, Germany

The influence of structural properties and interaction-induced effects on optical spectra of self-assembled Nitride-based quantum-dot (QD) systems is analyzed within a microscopic theory. Beside the QDs, the wetting-layer (WL) plays an important role for laser applications since it is involved in the carrier generation and scattering processes, which modify the optical properties of the QDs. The single-particle properties are determined on an atomistic level from tight-binding calculations [1]. Coulomb interaction effects and carrier-phonon interaction are considered in a second step to study excitation-induced effects for elevated carrier densities at room temperature.

Numerical results are presented for InN/GaN QD-WL systems. Nearly degenerate top valence-subbands lead to strong subband mixing [1, 2]. We also find modified dipole selection rules with a dark ground state exciton and rather strong excitation-induced line shifts of the QD transitions in addition to the excitation-induced line-broadening [3]. While these results are masked in conventional lasers due to strong inhomogeneous broadening, they are directly relevant for the application of QDs in microcavity lasers.

[1] S. Schulz et al., Phys. Rev. B 73, 245327(2006)

[2] S.L. Chuang et al., Phys. Rev. B 54, 2491(1996)

[3] M. Lorke et al., APL 95, 081108 (2009)