Band alignment at tellurium/MoS2 van der Waals heterojunction revealed by X-ray photoelectron spectroscopy

초록

Understanding interfacial band alignment is essential for elucidating charge transport dynamics and guiding the design of heterojunction-based optoelectronic applications. Two-dimensional van der Waals semiconductors offer unique opportunities to engineer interfacial electronic structures owing to their atomically sharp interfaces and reduced dimensionality. In this study, we systematically investigate the interfacial band alignment of a tellurium/molybdenum disulfide (MoS2) van der Waals heterojunction. The crystalline structures and vibrational characteristics of tellurium and MoS2 are confirmed by X-ray diffraction analysis and Raman spectroscopy analysis, respectively. High-resolution X-ray photoelectron spectroscopy (XPS) is conducted to quantitatively define the valence band offset using the Kraut method. The analysis reveals a staggered type-II band alignment at the tellurium/MoS2 interface with valence band offset (0.43 ± 0.05 eV) and conduction band offset (0.1 ± 0.05 eV), accompanied by pronounced core-level shifts indicative of interfacial band bending and charge redistribution. The experimentally extracted band offsets provide direct insight into carrier separation and transport behavior across the heterointerface and serve as quantitative design parameters for optoelectronic heterostructures. These results establish tellurium/MoS2 heterojunctions as a well-defined model system for interfacial band alignment studies and highlight the critical role of XPS-based band offset analysis in understanding and engineering van der Waals heterointerfaces. © 2026 Elsevier B.V.

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