Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Poster Session I

HL 13.27: Poster

Monday, March 12, 2018, 17:30–19:30, Poster B

Momentum-resolved hole and exciton dynamics in WSe₂ — •Patrick Xian, Michele Puppin, Christopher Nicholson, Martin Wolf, Laurenz Rettig, and Ralph Ernstorfer — Fritz-Haber-Institut der Max-Planck-Gesellschaft

Time-resolved ARPES (trARPES) is a unique tool for direct tracking of electronic dynamics in momentum space. We used a 500 kHz XUV source to photoemit electrons from the valence and conduction bands of WSe₂ following optical excitation of A excitons. We uncover the momentum dependence of various aspects of the excited state dynamics, in particular signatures of a bright to dark exciton transition. We extract bright exciton lifetimes with an optical Bloch equation model. The momentum dependence of the hole dynamics is retrieved by a global fitting algorithm that extracts the time dependence of 2D band structure parameters. Finally, we condensed our analysis pipeline into an open-source software package for trARPES data handling from 2D background removal to band position detection to multidimensional data visualization. Its Python implementation and support for Igor data formats invite public contribution and adoption.