Regensburg 2019 – wissenschaftliches Programm
HL 20.6: Vortrag
Dienstag, 2. April 2019, 15:15–15:30, H31
Non-equilibrium (Transient) Experiments on Zinc Oxide — •Shirly Espinoza1, Steffen Richter1, Oliver Herrfurth2, Mateusz Rebarz1, Stefan Zollner3, Marius Grundman2, Jakob Andreasson1,4, and Rüdiger Schmidt-Grund2 — 1ELI Beamlines, Institute of Physics, Czech Academy of Sciences, Czech Republic — 2Semiconductor Physics Group, Felix Bloch Institute for Solid State Physics, Leipzig, Germany — 3New Mexico State University, Department of Physics, Las Cruces, NM, USA — 4Condensed Matter Physics, Department of Physics, Chalmers University of Technology, Göteborg, Sweden
Zinc Oxide is a wide bandgap semiconductor considered for applications in electronics and optoelectronics devices. Its wide bandgap allows high power operation at high temperature; therefore, studies about its electron distribution at non-equilibrium values are crucial for the design of such device. Our work was done by pump-probe ellipsometry, a technique that allows the distinction between real and imaginary part of the dielectric function. We observed bleaching of the excitonic absorption at the band edge, and occurrence of intra-valence-band absorption during the very first picoseconds. Electron-phonon scattering causes thermalization, which creates non-thermal phonon distributions delaying the charge relaxation to tens of picosecond. The final heat dissipation happens in the scale of nanoseconds.