Ultrafast Exciton Dynamics Revealed

In semiconductors, electrons and holes can bind together via Coulomb interaction to form quasiparticles known as excitons. These are complex many-body systems, strongly influenced by screening and carrier–carrier interactions. Understanding their formation and evolution is key to uncovering the microscopic processes that underlie excitonic effects and to eventually harnessing them in optoelectronic and quantum technologies.

In a recent collaboration with the lab of Zhe Wang, where the ultrafast nonlinear terahertz (THz) spectroscopy measurements were performed, we analyzed the dynamics of exciton formation. Our results show that excitons form within just a few picoseconds after photoexcitation. Interestingly, the nonlinear response of excitons shows a nonmonotonic dependence on the electron–hole density. These findings offer new insights into the behavior of excitons and take us a step closer to fully understanding these intriguing quasiparticles.

This work was a collaboration with the group of Zhe Wang and Marc Assmann from TU Dortmund!