Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 55: Quantum dots: Interaction with environment

HL 55.7: Talk

Wednesday, March 18, 2015, 16:30–16:45, EW 203

Formation of bound continuum excitons due to excitonic effects in intraband quantum dot spectroscopy. — •Sandra Kuhn and Marten Richter — Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany

Coulomb induced effects on intraband transitions between bound quantum dot and unbound continuum states of the host material can play a role in a variety of experiments, due to their relevance to the dephasing properties of the quantum dot states as well as for bound to continuum intraband spectroscopy.

We present a theory based on the density matrix formalism to calculate bound to continuum intraband absorption spectra including Coulomb interaction. We study several bound to continuum quasi particles such as trions, biexciton or exciton, resulting in characteristic spectral signatures. In particular, our results show signatures of a bound exciton consisting of a localized carrier inside the quantum dot and a delocalized carrier of the continuum. To get information about the localization of this exciton we discuss the bound to continuum exciton wave function, which shows that the exciton is spatially delocalized in the vicinity of the quantum dot. Especially for the energetically higher states, the spatial extension of the exciton is much larger than the quantum dot extension of 10 nm, often up to 100 nm. This large wave function extension opens a way to study a new possibility of electronic coupling between different quantum dots.