Momentum-resolved hot electron dynamics at the 2H-MoS2 surface

Time- and angle-resolved photoelectron spectroscopy (trARPES) is employed to study hot electron dynamics in the conduction band of photoexcited 2H-MoS2. Momentum-dependent rise times of up to 150 fs after near-ultraviolet photoexcitation and decay times of the order of several-hundred fs allow us to locate areas of light absorption in the conduction-band energy landscape as well as to track the relaxation of hot electrons into the lowest-energy states. The conduction-band minima are finally depopulated within approximate to 1 ps, although a residual population remains up to the maximum investigated pump-probe delay of 15 ps. The presence of the fast depopulation channel differs from the results of experiments of bulk MoS2 performed with all-optical methods. It conforms, however, with recent findings for monolayer MoS2. We attribute this similarity to defect and surface states being of considerable relevance for the near-surface electron dynamics of bulk MoS2, as probed in a trARPES experiment.