Aspects of charge carrier dynamics in Germanium and cadmium zinc telluride

Abstract

This thesis addresses two markedly different aspects of ultrafast carrier dynamics in semiconductors in all-optical studies based on pump-probe measurements with femtosecond laser pulses. Both parts of the presented study aim to contribute to the fundamental understanding of the respective physical processes and to foster the applicability of the corresponding semiconductor systems in the context of spintronics, quantum computing, or all-optical switching. The first part of the present work provides an in-depth analysis of spin dynamics in the indirect semiconductor germanium. Founding on previously published work, the present study provides contributions to the understanding of the efficiency of the spin injection and readout process and their spectral dependencies, as well as the temporal limitations of the carrier spin ensemble coherence. The second part investigates the dynamical nonlinear optical response of the lower exciton-polariton branch in Cadmium Zinc Telluride. Motivated by the prospect of all-optical switching functionality, the question is addressed, to what extent the accompanying, highly nonlinear interaction induced by a high power laser pulse can be utilized to macroscopically manipulate the transmission of a second pulse on ultrashort time scales.