Many-Body Interaction Evidenced through Exciton-Trion-Electron Correlated Dynamics

Abstract

Interactions among excitons, trions, and electrons are studied in CdTe modulation-doped quantum wells. These many-body interactions are investigated through the nonlinear dynamical properties in the excitonic complexes using time and spectrally resolved pump and probe techniques. This study is performed as a function of temperature and densities of excitons, trions, and electrons. The results reveal that the nonlinearities induced by trions differ from those induced by excitons and moreover they are mutually correlated. The correlated behavior of excitons and trions manifests itself by crossed trion-exciton effects. We propose that the main source of these correlations is due to the presence of electrons in the quantum well and that its physical origin is the Pauli exclusion-principle. We find that, at 5 K, trions are formed from excitons within 10 ps; at 20 K a thermal equilibrium is reached within 5 ps.

Dressed excitons within an incoherent electron gas: Observation of a Mollow triplet and an Autler-Townes doublet

“…In addition, a reduced absorption of the excitonic high-energy tail is observed for + − configuration evidencing the reduction of the exciton-electron exchange scattering. 11,26 Note that by applying a light field resonantly to the exciton resonance, in a doped semiconductor quantum well, the transition can be coupled to the optical external field as well as it can experience internal interactions with the electrons. When the applied light field is weak, the internal field dominates and we measure the linear response to the weak perturbation, which is the excitonic absorption broadening mainly due to exciton-electron exchange interaction.…”