Ultrafast dynamics of photoexcited carriers in multiband semiconductor SnSe

We report time-resolved and angle-resolved photoemission spectroscopy on SnSe which currently attracts great interest due to their extremely high thermoelectric performance. Laser assisted photoemission signals are observed within ± 20 fs of the pump pulse arrival. Around 30–50 fs after the photoexcitation, the conduction band minima are not populated by the photoexcited electrons while the valence bands are considerably broadened. In going from 90 fs to 550 fs