Attosecond Carrier Dynamics and Electronic Structure Measurements in Quasi-2D Layered Materials

Two-dimensional layered materials may demonstrate strong quantum confinement effects not only in a single layer but perhaps already in quasi-2D layered crystals. Understanding such effects using electron dynamics would enable tailoring of electronic structure and interfaces of two-dimensional layered materials. Interrogating carrier dynamics on the relevant sub-fs to few-fs time-scales has however been challenging thus far. Here, we use attosecond spectroscopy to investigate quantum confinement effects for the carrier dynamics of SnS₂, MoS₂ and K-doped MoS₂. We demonstrate a layer decoupling mechanism due to strongly anisotropic screening, which leads to two-dimensional character manifest already in layered bulk crystals.