| AVS 64th International Symposium & Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Monday Sessions |
| Session EL+AS+EM-MoA |
| Session: | Spectroscopic Ellipsometry: Novel Applications and Theoretical Approaches |
| Presenter: | Mateusz Rebarz, ELI Beamlines - Czech Academy of Science, Czech Republic |
| Authors: | M. Rebarz, ELI Beamlines - Czech Academy of Science, Czech Republic S.J. Espinoza, ELI Beamlines - Czech Academy of Science, Czech Republic S. Richter, Universität Leipzig, Germany O. Herrfurth, Universität Leipzig, Germany R. Schmidt-Grund, Universität Leipzig, Germany J. Andreasson, Chalmers University of Technology, Sweden S. Zollner, New Mexico State University |
| Correspondent: | Click to Email |
The ongoing progress in miniaturization and operational rates of electronic and optoelectronic devices obliges materials scientists to deeply understand the dynamics of the carriers upon external electromagnetic stimulus in very short time scale. Some phenomena such as scattering of electrons and phonons as well as recombination processes can be as short as tens of femtoseconds. All these processes affect the temporal and local dielectric constants and determine many operational parameters of the devices. In this work, we report on recent progress in developing a spectroscopic ellipsometer for characterization of ultrafast dynamic changes of dielectric properties in materials and photonic structures technologically relevant in optoelectronics. Our time-resolved ellipsometer is based on pump-probe technique and offers monitoring the time evolution of the dielectric properties in range 0-5 ns with time resolution ~100 fs in broadband spectral range (340-750 nm).
We present here the results of the measurements performed on Ge samples in comparison with theoretical predictions. Ultrafast phenomena such as excitation, relaxation and diffusion of charge carriers, band-gap renormalization and excitons screening will be discussed. In addition we report on the first data obtained from a ZnO-based planar microcavity especially on the temporal evolution of the microcavity modes. The time evolution of the ellipsometric parameters in the spectral range around the exciton-polariton mode will be discussed. We observed that such modes disappear upon the excitation, possibly due to screening of the excitons and re-appear after a few hundreds of femtoseconds as blueshifted modes. The investigation of the short-time dynamics of such modes can stimulate new theoretical approaches for the description of exciton-polariton systems.