Fig. 1: Schematic of resonant exciton pumping and carrier relaxation dynamics.
From: Mid-IR probing unveils vanadium doping-induced unsaturation of defect states in monolayer MoS2
a Pumping at A (1.85 eV, red) or B (2 eV, green) resonances and subsequently probing with 0.31 or 0.62 eV. The low-energy probe (0.31 eV) resolves intra-excitonic levels; the corresponding band splitting is illustrated. The grey arrow in a shows the exciton binding energy (Eb = 0.4–0.5 eV). The conduction band (CB) is shaded in grey. b The relaxation pathways at both probe energies. The excitons dissociate and form the hot carriers above the Mott density due to bandgap renormalization (BGR). Orange dashed lines indicate the Vanadium-induced localized states near the conduction and valence bands. Curved arrows represent exciton relaxation into the defect levels, while the grey curved arrow indicates radiative recombination of electrons into the valence band. For clarity, the CB splitting is exaggerated; in reality, the valence band splitting is an order of magnitude larger. Rydberg-like excitonic levels are shown only in the conduction band for schematic simplicity.
