Atomic-scale control over band alignment in single-layer lateral heterostructures (LHSs) of dissimilar transition metal dichalcogenides (TMDCs) is critical for nextgeneration electronic, optoelectronic, and quantum technologies. However, direct experimental access to interfacial electronic states with nanometer precision remains a significant challenge. Here, we employ angle-resolved photoemission spectroscopy with nanoscale spatial resolution (nanoARPES) to directly map the epitaxial alignment and valence band evolution across MoSe2-WSe2 LHSs. By combining nanoARPES with spatially resolved photoluminescence, we correlate the evolution of the valence band maximum and exciton features across both atomically sharp and compositionally graded diffusive interfaces. We identified type-II band alignments governed by both material composition and interstitial-induced modifications of band offsets, in close agreement with density functional theory calculations. These results reveal fundamental mechanisms of electronic structure modulation at 1D TMDC heterointerfaces and provide a robust platform for tailored band engineering in van der Waals materials.
@article{arxiv.2602.03321,
title = {Direct nanoscale mapping of band alignment in single-layer semiconducting lateral heterojunctions},
author = {Chakradhar Sahoo and Suman Kumar Chakraborty and A. Kousika and Alfred J. H. Jones and Manas Sharma and Thomas S. Nielsen and Zhihao Jiang and Ihsan A. Kolasseri and Subhadip Das and Matthew D. Watson and Cephise Cacho and Kenji Watanabe and Takashi Taniguchi and Yong P. Chen and Tony F. Heinz and Ananth Govind Rajan and Prasana K. Sahoo and Søren Ulstrup},
journal= {arXiv preprint arXiv:2602.03321},
year = {2026}
}