Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 66: Ultrafast electron dynamics at surface and interfaces III

O 66.1: Invited Talk

Wednesday, March 11, 2026, 15:00–15:30, TRE/MATH

Ultrafast exciton dynamics in 2D semiconductors and electric field gated devices — •Jan Philipp Bange — Georg-August-Universität Göttingen, I. Physikalisches Institut, Germany

Two-dimensional (2D) semiconductors and moiré materials, formed by stacking and twisting atomically thin layers, provide an exciting platform to discover and engineer new quantum states. Precise and reversible control of carrier density and many-body effects is readily achieved through in-situ electric field gating. In combination with angle-resolved photoemission spectroscopy this has been a powerful probe of the static electronic band structure. However, capturing the ultrafast dynamics of excited states in gated 2D materials, including hybrid excitons [1], interlayer excitons [2], and trions [3], remains a fundamental challenge due to the limited real-space resolution of ultrafast time- and momentum-resolved spectroscopy techniques. In this talk, I will present how time-resolved momentum microscopy provides direct access to both the energy landscape and femtosecond dynamics of bright and dark excitons at nanometer length scales. This methodology enables the disentanglement of electron and hole transfer pathways across twisted transition metal dichalcogenide interfaces and reveals the ultrafast formation of quasiparticles as a function of gate voltage.

[1] Bange et al., Science Advances 10, eadi1323 (2024).

[2] Schmitt et al., Nature Photonics 19, 187 (2025).

[3] Meneghini et al., arXiv.2511.11448 (2025).

Keywords: Momentum microscopy; Exciton; in-situ electric field gating; Ultrafast dynamics; Dark field imaging