Growth of Highly Oriented (VNbMoTaW)S₂ Layers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Compositional tunability is key for advancing van der Waals (vdW) layered materials like transition-metal dichalcogenides (TMDCs).
• Current methods for creating multielement alloy TMDC layers rely on exfoliation from bulk powders, limiting control and scalability.

Purpose of the Study:

• To demonstrate a novel synthesis route for directly depositing high-entropy alloy TMDC layers with controlled compositions and thicknesses.
• To explore the heteroepitaxial growth of these advanced materials on various substrates.

Main Methods:

• Ultra-high-vacuum reactive dc magnetron sputtering of a VNbMoTaW target in Kr and H2S gas mixtures.
• Characterization using density functional theory, Raman spectroscopy, X-ray diffraction, STEM-EDX, and XPS.

Main Results:

• Successfully deposited single-phase, 2H-structured, 0001-oriented (V0.10Nb0.16Mo0.19Ta0.28W0.27)S2.44 high-entropy alloy layers.
• Demonstrated controllable layer thickness on graphene and Al2O3(0001) substrates (with and without hBN).

Conclusions:

• The developed sputtering technique offers a general and versatile method for synthesizing a wide range of TMDC alloys.
• This approach facilitates the creation of custom-composition multielement alloy vdW compounds for future material innovations.