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 71.15: Poster
Mittwoch, 11. März 2026, 18:00–20:00, P2
STM study on tuning the Fermi level of transition metal dichalcogenides — •Nguyen-Hoang Dang1, Mincheol Kim2, Ganbat Duvjir1, Young Jun Chang2,3, and Jungdae Kim1 — 1Department of Semiconductor Physics and Engineering, University of Ulsan, Ulsan 44610, Republic of Korea — 2Department of Physics, University of Seoul, Seoul 02504, Republic of Korea — 3Department of Smart Cities, University of Seoul, Seoul 02504, Republic of Korea
Controlling the Fermi level is essential for tailoring the electronic properties of semiconductors. Here, we investigate two routes of chemical doping and defect control using scanning tunneling microscopy and spectroscopy. For V-doped MoSe2, we study how substitutional V atoms influence its electronic structure. Although STM primarily probes the top Se layer and the dopants are not directly imaged, the topography exhibits defect-like features whose contrast reverses with the bias polarity: dark at positive sample bias and bright at negative bias. This is characteristic of negatively charged acceptor states, consistent with V substituting Mo. STS spectra show a Fermi-level shift toward the valence band, indicating that V doping drives MoSe2 from intrinsic n-type toward p-type. For HfSe2, we study defect control via thermal annealing. STS measurements under different annealing conditions show Fermi level shifts toward the conduction band, suggesting that prolonged annealing enhances Se-vacancy formation, which acts as an electron donor. These results highlight how STM/STS links local defects with electronic properties, offering microscopic insight into Fermi level tuning through doping and defect engineering.
Keywords: STM; STS; TMDs; negatively charged; Fermi level