MoSi₂N₄ and the MA₂Z₄ family

MA₂Z₄ (M = Mo, W, V, Ta…; A = Si, Ge; Z = N, P, As)

Also called WSi₂N₄, MA₂Z₄

nanosheet semiconductor

A 2D material with no parent crystal to peel. Molybdenum nitride is not layered, but adding silicon during growth caps each nitride layer with silicon–nitrogen bilayers, and the result – MoSi₂N₄ – comes out of the reactor as centimetre-scale monolayer film. It is a semiconductor with a gap near 2 eV, is strong, and is stable in air, and calculations say it is the first member of a large family built the same way, which makes it a rare case of a 2D material designed rather than discovered.

Data sheet

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Kind of sheet: nanosheet
Made by chemistry or cut from a solid, not peeled as a clean crystal layer
Behaves as: semiconductor
Band gap: ~1.94 eV for monolayer MoSi₂N₄; the family spans semiconductors, metals and predicted magnets

In colour: this family, 1.94 eV. In grey: the other 39 families on the catalogue’s chart, each at the middle of its range.
Thickness: ~1 nm per septuple layer
Structure: A septuple atomic layer, N–Si–N–Mo–N–Si–N: a MoN₂ layer sandwiched between two Si–N bilayers, which is also how the wider family is built – a dichalcogenide-like MZ₂ layer intercalated into an InSe-like A₂Z₂ layer
Stability: Stable in air and water, which is one of its selling points against etched nitride and carbide monolayers, whose surfaces oxidise. The silicon–nitrogen layers do the protecting.
First made: Grown in 2020 (Hong and colleagues), who also predicted the wider family; the MA₂Z₄ construction rule was set out in 2021 (Wang and colleagues)

Compare with other materials

Key properties

Grown directly as monolayer films centimetres across, by adding silicon during chemical vapour deposition of molybdenum nitride
Band gap ~1.94 eV as a monolayer, in the visible range and wider than most TMDC monolayers
High mechanical strength (~66 GPa) and good stability in air and water, unlike etched nitride monolayers
Outer Si–N layers shield the inner MoN₂ layer, which is why its valley properties survive contact with other materials
Calculations predict dozens of stable MA₂Z₄ compounds, sorted by valence-electron count: semiconductors at 32 and 34 electrons, metals or ferromagnetic semiconductors at 33
Among the predictions are a ferromagnetic semiconductor (VSi₂P₄), an Ising superconductor (TaSi₂N₄) and direct-gap semiconductors (WSi₂P₄)

How it is made

Chemical vapour deposition on copper foils or similar substrates, with elemental silicon added to passivate the growing nitride surface
Multilayers and heterostructures are stacked from grown films rather than exfoliated from a bulk crystal
Most family members beyond MoSi₂N₄ and WSi₂N₄ exist only in calculations so far

Uses, and how close they are

Wide-gap channels and barriers for 2D electronicslab
Valleytronics and spin–valley deviceslab
Photocatalysis and protective coatingslab

Readiness runs lab → prototype → pilot → deployed.

Open problems

Can any of the predicted MA₂Z₄ compounds beyond MoSi₂N₄ and WSi₂N₄ be grown?
What limits carrier mobility and contact resistance in grown films, where measurements so far lag behind the calculations?
Does growth ever give a controlled number of layers, given there is no bulk crystal to exfoliate from?
Are predicted magnetism and Ising superconductivity in the family real, or artefacts of idealised calculations?

Going deeper

Short notes for specialists. Choose a lens in the header and yours comes first.

For theoreticians · your lens

MA₂Z₄ is a construction rule rather than a mineral: take an MZ₂ layer of the MoS₂ type and intercalate it into an A₂Z₂ layer of the InSe type, and the combination reconstructs both band structures. Electron counting then organises the family – 32 and 34 valence electrons give semiconductors, 33 gives metals or ferromagnetic semiconductors – which makes it a clean test case for high-throughput screening, since dozens of members are predicted stable but only two are grown. In MoSi₂N₄ itself the valence and conduction band edges sit at K, giving spin–valley coupling like a TMDC, with the outer Si–N layers screening the active MoN₂ layer from its surroundings.

For experimentalists · your lens

Growth is the whole game: silicon is what stops molybdenum nitride from forming islands, so the silicon supply and its timing set film quality. Because there is no bulk crystal, thickness cannot be checked by exfoliation habits – calibrate Raman and optical contrast against AFM on the grown film. Expect the reported mobilities to depend heavily on transfer and contacts, and report both growth substrate and transfer route.

For engineers · your lens

The appeal is a wide-gap 2D semiconductor that grows over centimetres and survives air, without the etching step that MXenes need. Against that: mobility and contact resistance are unproven at device level, there is no bulk source for exfoliation, and only two members of the predicted family exist in the lab. Treat it as a material to watch rather than one to design around.

In the research tracks

Theory frontiers

High-throughput discovery and 2D databases

Growth methods

Powder-source CVD of TMDC monolayers

Recent news

The newest items tagged MoSi₂N₄, from the news feed updated 5 Oct 2026.

Preprintnot yet peer reviewed 30 Sep 2026 arXiv

Polymorph-Tunable Spin Texture and Excitonic Structures in Monolayer WSi2P4

Two-dimensional semiconductors that simultaneously possess a direct band gap and strong spin-orbit coupling (SOC) are highly attractive for quantum optoelectronics. Using first-principles GW plus Bethe-Salpeter equation (GW-BSE) calculations, we show that monolayer WSi2P4-an experimentally accessible member of the…

TheoryMoSi₂N₄

All 1 item tagged MoSi₂N₄ in the news feed · RSS feed for MoSi₂N₄

Key references

Chemical vapor deposition of layered two-dimensional MoSi₂N₄ materialsHong et al. · Science 369, 670 (2020)cited by 1,140doi:10.1126/science.abb7023
Intercalated architecture of MA2Z4 family layered van der Waals materials with emerging topological, magnetic and superconducting propertiesWang et al. · Nature Communications 12, 2361 (2021)cited by 467doi:10.1038/s41467-021-22324-8
Spin-valley coupling and valley splitting in the MoSi₂N₄/CrCl₃ van der Waals heterostructureZhao et al. · Applied Physics Letters 119, 213101 (2021)cited by 50doi:10.1063/5.0072266