Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 6: Ultrafast Phenoma I

HL 6.3: Vortrag

Montag, 20. März 2017, 10:15–10:30, POT 51

Atomistic modeling of exciton and charge dynamics in a ZnO nanocrystal — •Dirk Ziemann and Volkhard May — Institut für Physik, Newtonstr. 15, Humboldt Universität zu Berlin, D-12489 Berlin, Germany

There is an increasing interest in ZnO semiconductor materials due to, i. a., its wide band gap and large exciton binding energy. Especially ZnO nanostructures are promising candidates for modern optical and opto electronic devices. For a quantitative understanding of the processes and time scales in theses systems an atomistic description of realistic systems, which are tens of nanometers in size and consist of thousands of atoms, is needed.

Therefor, in this talk the dynamics of excitons and charges in a spherical ZnO nanocrystal (10.000 atoms) will be discussed. The dynamics are described by a stochastic Schrödinger equation taking the initial photoexcitation and the subsequent relaxtion via electron/exciton phonon interaction into acount. The electronic and phononic states are modeled by the density functional based tight binding (dftb) method, which deals with huge systems and is still able to consider, e. g., surface effects, ligands und defects on an atomistic level. Excitonic states are calculated with a configuration interaction (CI) approach.