Dynamics of light-induced self-intercalation in TaS2

Chemical intercalation in transition metal dichalogenides (TMDs) has long since attracted attention as an effective method of modifying the electronic landscape, the interactions between layers across the van-der-Waals gap, and even in electrochemical energy storage for battery technology. There have been recent advances in the fabrication of intercalated TMDs, including molecular-beam epitaxy and chemical vapor deposition methods. Here, we report a novel method of self-intercalation in 1T-TaS2 via application of near-infrared light pulses, with tunable tantalum concentration by varying exposure time as well as pulse energy. Using time-resolved electron diffraction, we further characterize the dynamics of the intercalated tantalum atoms, in comparison to that of the host lattice, after pulsed photoexcitation. We also report a reversible phase transition in which the diffraction peaks associated with the tantalum intercalates disappear and reappear near a critical temperature, corresponding to a transition analogous to sublimation. Our results may provide effective avenues for intercalation of other TMDs, an important area of interest for battery technology.