Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 26: Ultra-fast phenomena

HL 26.6: Talk

Wednesday, March 14, 2018, 10:45–11:00, EW 202

The role of the Σ-point in the ultrafast dynamics of intervalley hole scattering in PbTe — •Prashant Padmanabhan, Manpreet Kaur, Kestutis Budzinauskas, and Paul H. M. van Loosdrecht — II. Physics Institute, University of 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 investigate the ultrafast relaxation of highly excited carriers, probing the dynamics of electron-phonon interactions on the femtosecond and picosecond time-scales. Our experimental and theoretical results show that phonon-mediated intervalley scattering involving the Σ-point plays a significant role in the hole cooling process due to the unique topology of its valence band. In addition, anomalous temperature dependencies in the carrier relaxation rates show the dramatic influence of the softening of phonons characteristic of incipient ferroelectrics.