Regensburg 2025 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 8: 2D Semiconductors and van der Waals Heterostructures II

HL 8.2: Vortrag

Montag, 17. März 2025, 15:15–15:30, H15

Modifying properties of 2D transition metal dichalcogenides by confined-space annealing — •Christian Tessarek, Christian Petersen, Tim Grieb, Florian F. Krause, Alexander Karg, Christian Habben, Andreas Rosenauer, and Martin Eickhoff — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany

2D transition metal dichalcogenides (TMDs) can be grown by different methods, e.g. chemical vapor or atomic layer deposition (ALD) [1]. Subsequent annealing is often applied to improve the properties of the as-grown 2D layers. Decomposition of TMD layers due to desorption of chalcogenides usually limits the temperature range. Higher annealing temperatures are possible in a chalcogene containing atmosphere but require special safety requirements of the annealing equipment.

In this study, a confined-space annealing (CSA) approach is demonstrated and realized by a close contact face-to-face sample arrangement of TMD layers on SiO₂/Si or graphene substrates. CSA is performed in vacuum or in an inert gas atmosphere without using additional chalcogene containing precursors. Such sample arrangement strongly reduces chalcogene outdiffusion from the confined space and allows annealing at higher temperatures and longer durations. The influence of CSA parameters is investigated with respect to structural and optical properties of the TMDs and compared to a standard annealing process of uncovered layers. It will also be shown that CSA can be used for conversion of MoS₂ to ternary Mo(S,Se)₂ and binary MoSe₂.

[1] C. Tessarek et al., 2D Mater. 11, 025031 (2024).

Keywords: Transition metal dichalcogenides; MoS2; Annealing; Raman spectroscopy; Photoluminescence spectroscopy