Ultrafast dynamics with time-resolved ARPES: Photoexcited electrons in monochalcogenide semiconductors

Time-resolved ARPES makes it possible to directly visualize the band dispersion of photoexcited solids, as well as to study its time evolution on the femtosecond time scale. In this article, we show how this technique can be used to monitor the ultrafast hot carrier dynamics and the conduction band dispersion in two typical monochalcogenide semiconductors: direct band gap, n-type indium selenide and indirect band gap, p-type germanium selenide. With this approach, one can directly estimate the effective electron masses of these semiconductors. Moreover, the dynamics of hot electrons in the two semiconductors are analyzed and compared. Our findings provide valuable information for the use of monochalcogenide semiconductors in future optoelectronic devices.