Fabrication and Characterization of Transition Metal Dichalcogenide Films

Transition metal dichalcogenide (TMDC) films, comprising layers of a transition metal sandwiched between two chalcogen atoms, have emerged as versatile two-dimensional semiconductors. Fabrication approaches fall broadly into top-down and bottom-up strategies. Top-down methods, including mechanical and liquid-phase exfoliation, and precision thinning by plasma or laser, enable access to monolayer and few-layer films with minimal chemical contamination. Bottom-up synthesis typically employs chemical vapour deposition or metal-organic chemical vapour deposition to produce large-area films directly on substrates, offering control over layer number, crystallinity and heterostructure formation. Pulsed laser deposition and atomic layer deposition further extend this toolkit by permitting high-quality film growth under controlled stoichiometry and thickness. Characterization of TMDC films relies on a suite of microscopy and spectroscopic techniques. Transmission electron microscopy reveals atomic structure and grain boundaries; atomic force microscopy maps topography and thickness; Raman spectroscopy distinguishes layer number and crystal phase; and photoluminescence spectroscopy probes electronic band structure and defect states. Complementary electrical and optical transport measurements assess carrier mobility, on/off ratios in field-effect transistors, and excitonic emission efficiency. Together, these advances underpin the integration of TMDC films into next-generation electronics, optoelectronics, sensing platforms and catalysis for hydrogen evolution, bearing global significance for energy and information technologies.

Research from Nature Portfolio

Recent studies have provided direct insight into the growth mechanisms of TMDC films and refined techniques for precise thinning. In situ transmission electron microscopy has revealed discrete stages of MoS₂ flake formation from thermolysed precursors, demonstrating temperature-dependent transitions from vertically aligned layers to horizontal sheets and eventual grain coalescence, thereby informing strategies to control orientation and crystal size. A soft plasma-etching process employing a mild SF₆/N₂ mixture has achieved uniform atomic-layer removal of MoS₂, tunable to reach sub-monolayer precision without substrate damage, and preserving vibrational and photoluminescent signatures of the remaining layers. Laser-induced thinning and patterning of MoS₂ films has delivered layer-by-layer vertical and lateral control via calibrated fluence and exposure, enabling the fabrication of bespoke multilayer junctions for three-dimensional device architectures.

Fabrication and Characterization of Transition Metal Dichalcogenide Films publication trend

The graph below shows the total number of articles in fabrication and characterization of transition metal dichalcogenide films across all publications each year (not limited to Nature Index journals).

Technical terms

Transition metal dichalcogenide (TMDC): A layered material of form MX₂, where M is a transition metal and X a chalcogen, exhibiting two-dimensional properties.

Chemical vapour deposition (CVD): A bottom-up synthesis technique in which gaseous precursors react on a substrate to form thin films.

Transmission electron microscopy (TEM): A high-resolution imaging method that passes electrons through a thin sample to reveal atomic structure.

Atomic force microscopy (AFM): A technique that scans a sharp tip over a surface to map nanoscale topography and thickness.

Raman spectroscopy: A vibrational spectroscopic method used to identify crystal phase, strain and layer number in 2D materials.

Photoluminescence (PL): The emission of light from a material following optical excitation, indicative of band-gap and defect states.

Plasma etching: A dry etching process using ionised gas to selectively remove atomic layers from a substrate.

References

1. Layer-by-layer thinning of two-dimensional materials. Chemical Society Reviews (2024).
2. Structural Instability Stimulated Heteroatoms Co‐Doping of 2D Quaternary Semiconductor for Optoelectronic Applications. Advanced Functional Materials (2023).
3. 2D materials advances: from large scale synthesis and controlled heterostructures to improved characterization techniques, defects and applications. 2D Materials (2016).
4. Direct TEM observations of growth mechanisms of two-dimensional MoS2 flakes. Nature Communications (2016).
5. Atomic-layer soft plasma etching of MoS2. Scientific Reports (2016).
6. Laser Thinning and Patterning of MoS2 with Layer-by-Layer Precision. Scientific Reports (2017).
7. Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition. APL Materials (2015).