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HL: Fachverband Halbleiterphysik

HL 63: Poster: Quantum Dots and Optics

HL 63.11: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P1A

The role of intervalley scattering and phonon softening in the ultrafast carrier dynamics of PbTe — •Manpreet Kaur, Prashant Padmanabhan, Kestutis Budzinauskas, and Paul van Loosdrecht — Physics Institute 2, University of Cologne, 50937 Cologne, Germany

PbTe is a leading thermoelectric material, notable for its low thermal conductivity and large carrier mobility at low doping levels. Using time-resolved differential reflectivity measurements, we shed light on the ultrafast relaxation of highly excited carriers, probing the dynamics of electron-phonon interactions on the femtosecond and picosecond time-scales. Our results suggest that phonon-mediated intervalley scattering involving the Σ-point band gap plays a significant role in the carrier cooling process due to its unique energy dispersion. In addition, anomalous temperature dependencies in the carrier relaxation rates support recent observations of giant anharmonic interactions between LA and TO phonons in this material.