Effects of charge injection on ultrafast semiconductor dynamics

Charge injection into a junction of a semiconductor with another material is a resource widely used in electronics, but little explored for applications in optics despite the great potential it offers. Ultrafast spectroscopy techniques provide useful information to understand the nature of a phenomenon in materials, and thus their potential applicability in new technologies. In this work, two ultrafast spectroscopy experimental setups are proposed to study, firstly, the effect of charge injection on the formation of collective excitations in matter and, secondly, to understand how charge injection affects dynamical parameters such as electron mobility. In the first setup, which consists of a pump-push-probe scheme inducing an independent charge injection and excitation density in a medium, it is concluded that in a $WS_2$(bulk)-Au junction, charge injection affects the exciton formation dynamics as a function of the ratio between the injected and the excited charge density. In the second experiment, two complementary measurements via Pump-Probe experiments are proposed: The first one measuring for transient conductivity, via a probe in the few THz range, and the second one for transient white light reflection, in order to draw solid conclusions on the effect of the extracted charges on the electronic dynamics in junctions of a CIGS (photovoltaic cells)-buffer layers.