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arXiv · 2511.16758

Tungsten doping-induced phase transition in CVD-grown MoS2 bilayers

Ana Senkić·Rachael Keneipp·Petra Ivatović·Namrata Pradeep·Vincent Meunier·Marko Kralj·Marija Drndić·Nataša Vujičić
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Abstract

Controlling the crystal phase of two-dimensional (2D) transition metal dichalcogenides (TMDs) is essential for tailoring their optical and electronic properties. While phase transitions in monolayer TMDs and semiconductor-to-metal conversions have been widely studied, structural transitions between semiconducting polytypes - particularly in bilayer (2L) systems - remain underexplored. Here, we demonstrate a W doping-induced phase transition from non-centrosymmetric AA stacking to centrosymmetric AB' in 2L MoS2 synthesized by chemical vapor deposition (CVD). Using polarization-resolved second harmonic generation (SHG) and low-frequency Raman spectroscopy, we identify a phase transition correlated with increasing tungsten (W) concentration. The dilute W-doped 2L system exhibits a vanishing SHG signal and a stiffening of the layer-breathing (LB) vibrational mode, in contrast to undoped samples with strong SHG and a softer LB mode. Aberration corrected scanning transmission electron microscopy (AC-STEM) demonstrates the spatial distribution of W concentration and associated structural changes. These findings highlight W-doping as an effective strategy for inducing phase transitions in 2L TMDs, opening new possibilities for engineered heterostructures, phase-controlled device applications or as a source of single photon emitters.

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Ana Senkić, Rachael Keneipp, Petra Ivatović, Namrata Pradeep, Vincent Meunier, Marko Kralj, Marija Drndić, Nataša Vujičić. 2025-11-20. Tungsten doping-induced phase transition in CVD-grown MoS2 bilayers. https://arxiv.org/abs/2511.16758

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