Fig. 1: Spatiotemporal dynamics of suspended trilayer, bilayer and monolayer MoSe2.
a Schematic view of a suspended MoSe2 flake over a hole with a diameter of 15 μm. A pump and a probe beam impinge on the sample at controlled Δx and Δt. b Piezo scanning map acquired with the pump (1.2 μJ/cm2) and probe beams overlapped in time and space. c Normalized spatiotemporal map where both Δx and Δt are varied, showing the spatial spreading of the photoexcitation in time in the bilayer sample. d–f Time-resolved measurements, showing the transient reflectivity as a function of Δt, with Δx = 0, for a suspended trilayer (d), bilayer (e) and monolayer (f) at 20 μJ/cm2, 10 μJ/cm2 and 1 μJ/cm2 respectively. Solid lines indicate the exponential fit. g–i Spatiotemporal measurements, showing the extracted squared width as a function of Δt for a suspended trilayer (g), bilayer (h) and monolayer (i) at 20 μJ/cm2, 0.2 μJ/cm2 and 0.2–1 μJ/cm2 respectively. Multiple measurements are represented for each thickness, represented by different colors. The datasets with the darker orange colors in (g) have been vertically shifted to match the light orange dataset, which is the one acquired with the same alignment as the other thicknesses. The solid line in panel (g) represents trap-limited diffusion. The gradual color bars on top of panels (g–i) represent different regimes of diffusion.
