Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties

HL 91.16: Poster

Donnerstag, 14. März 2013, 16:00–20:00, Poster A

Carrier multiplication in a multi-level, colloidal quantum dot under the presence of phonons — •Mario Schoth, Franz Schulze, Andreas Knorr, and Marten Richter — Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Germany

Carrier multiplication (CM) in quantum dots (QD) has been proposed as a possible technique to further increase the efficiency of photovoltaic conversion [1,2]. In this process, the Auger-type Coulomb processes of impact ionization and Auger recombination lead to the creation of multiple electron–hole pairs per absorbed high–energy photon. The efficiency of such processes is reduced by competing relaxation channels, such as radiative recombination or relaxation via phonons [3]. In this contribution, we present a microscopically derived, dynamical model of CM in a single, multi-level, colloidal QD, where we consider the electron–electron- as well as the electron–phonon interaction. The finite size of the colloidal QD gives rise to a discretization of phonon modes, which we calculate for a spherical QD [4]. Using this parameter–free approach, we simulate the dynamics of exciton creation and annihilation, and investigate if CM is enhanced or suppressed by phonons.
[1] A.J  Nozik, Physica E 14, 115 (2002)
[2] R.D. Schaller and V.I. Klimov, Phys. Rev. Lett. 92, 186601 (2004)
[3] F. Schulze, M. Schoth, U. Woggon, A. Knorr, and C. Weber, Phys. Rev. B 84, 125328 (2011)
[4] T. Takagahara, J.  Lumin. 70, 129 (1996)