Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 71: 2D Materials: Electronic structure, excitations, etc. – Poster (joint session O/TT)

O 71.9: Poster

Mittwoch, 11. März 2026, 18:00–20:00, P2

Band structure and Work Function in Ultrathin HfSe2 — •Young Jun Chang — University of Seoul, Seoul, Republic of Korea

Two-dimensional (2D) transition metal dichalcogenides (TMDs) exhibit significant modifications in their electronic structures when reduced from bulk to monolayer thickness. In this study, we investigated the thickness-dependent electronic properties of epitaxial 1T-HfSe2 thin films. The films were grown via molecular beam epitaxy (MBE) and monitored in situ by reflection high-energy electron diffraction (RHEED). Scanning tunneling microscopy (STM) revealed atomically flat surfaces with well-defined 1T hexagonal lattices, while scanning tunneling spectroscopy (STS) measured a bandgap of ~1.1 eV for the monolayer. Angle-resolved photoemission spectroscopy (ARPES) revealed thickness-induced band splitting in the valence band, while the valence band maximum (VBM) remained pinned regardless of thickness. In contrast, the work function increased monotonically with film thickness. Density functional theory (DFT) calculations reproduced the observed band structures and attributed the thickness-dependent work function to the screening effect of the underlying graphene substrate. These findings provide key insights into band alignment and interface engineering in 2D semiconductor-based electronic and optoelectronic devices. (RS-2023-00220471, RS-2023-00284081, RS-2024-00334854)

Keywords: TMD; HfSe₂; MBE; ARPES; STM