The Topography Trap: Sifting Interlayer Excitons from Strain-Related Artifacts in Real-World 2D Heterostructures

@misc{lopez2026topography,
  title = {{The Topography Trap: Sifting Interlayer Excitons from Strain-Related Artifacts in Real-World 2D Heterostructures}},
  author = {Pablo Hernández López and Luka Pirker and Astrid Weston and Arijit Kayal and Rafael Nadas and Adrián Dewambrechies Fernández and Roman Gorbachev and Kirill I. Bolotin and Tim Verhagen and Álvaro Rodríguez and Otakar Frank and Sebastian Heeg},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2605.20869},
  eprint = {2605.20869},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2605.20869},
}

TY  - UNPB
TI  - The Topography Trap: Sifting Interlayer Excitons from Strain-Related Artifacts in Real-World 2D Heterostructures
AU  - Pablo Hernández López
AU  - Luka Pirker
AU  - Astrid Weston
AU  - Arijit Kayal
AU  - Rafael Nadas
AU  - Adrián Dewambrechies Fernández
AU  - Roman Gorbachev
AU  - Kirill I. Bolotin
AU  - Tim Verhagen
AU  - Álvaro Rodríguez
AU  - Otakar Frank
AU  - Sebastian Heeg
PY  - 2026
DA  - 2026/10/29
PB  - arXiv
DO  - 10.48550/arxiv.2605.20869
UR  - https://arxiv.org/abs/2605.20869
AB  - Novel excitonics emerging in transition metal dichalcogenide (TMDC) heterostructures belong to the most exciting topics in contemporary physics of van der Waals materials. Interlayer excitons (IXs) stand out among those due to their long radiative lifetimes and tunability by electric fields, strain, and twist angle. However, many ambiguities persist in the optical identification and manipulation of IXs, highlighting the need for reliable spectroscopic criteria that distinguish interlayer species from spurious signals. Here, we introduce a decision-tree protocol that evaluates interlayer coupling via intralayer exciton quenching and correlates photoluminescence (PL) with atomic force microscopy to establish IX-compatibility of room-temperature PL features in TMDC-based heterostructures. Applied to MoS_2-MoSe_2 and MoS_2-WSe_2 heterostructures, it recovers the established momentum-direct IX between the K valleys of the two layers (KK-IX). In WS_2-WSe_2, a low-energy feature persists through flat, well-coupled regions and for both stacking orders, supporting its assignment as IX-compatible. In contrast, we find no compelling evidence that the widely reported bright, momentum-indirect, twist-angle-independent ΓK-IX signature in MoS_2-WSe_2 originates from interlayer emission. Comprehensive experimental data, including infrared and tip-enhanced photoluminescence, stacking order inversion, interface cleaning, control measurements on WSe_2/Au, and statistics on variously prepared samples, instead trace these features to locally decoupled and strained WSe_2 at interface bubbles and topographical irregularities. Our results expose a generic "topography trap" in real-world heterostructures and establish a practical minimum standard for robust IX assignments, the sift-IX protocol, through spatially resolved room-temperature optical and topographic characterization.
ER  -