Tungsten disulfide
WS₂Also called tungstenite (mineral)
Molybdenum disulfide’s tungsten twin, and in many ways the better light emitter: a single layer glows orange-red with the highest photoluminescence efficiency of the common TMDCs. The heavier tungsten atom brings stronger spin–orbit coupling, which matters for devices that use an electron’s spin or valley.
Crystal structure
They are coordination polyhedra. Only complete ones are drawn.
Three layers of 2H-WS2, stacked like molybdenite: each layer is turned by 180° against the one below, so tungsten sits over sulfur, and every second layer repeats. c = 12.32 Å. A stack with an even number of layers has an inversion centre; one with an odd number does not. Cell from Schutte, de Boer and Jellinek, Journal of Solid State Chemistry 70, 207 (1987); COD 9012191.
Three layers of 3R-WS2. Each layer is shifted by the same step in the same direction, so sulfur sits over tungsten and the pattern repeats only after three layers: c = 18.49 Å. A 3R crystal has no inversion centre at any thickness, so it keeps the single layer’s second-harmonic generation as layers are added. Cell from Schutte, de Boer and Jellinek, Journal of Solid State Chemistry 70, 207 (1987); COD 9012192.
- W
- S
- Cell
- Hexagonal, a = 3.15 Å
- Atoms per cell
- 3
- W–S bond
- 2.40 Å
- Height
- 3.14 Å between the outer atom centres
Key properties
- Monolayer A exciton at ~2.0 eV (~620 nm) with bright room-temperature photoluminescence
- Valence-band spin–orbit splitting at K of ~400 meV
- Exciton binding energy ~0.3 eV for monolayers on SiO2, with a non-hydrogenic Rydberg series
- Spin-dark exciton ground state: the bright exciton lies above a dark state, so emission characteristics change strongly with temperature
- Electron mobility in CVD monolayers typically tens of cm2/(V·s) at room temperature
How it is made
- CVD from WO3 and sulfur, often with NaCl to lower the oxide’s vaporisation temperature
- MOCVD from W(CO)6 – wafer-scale films, including 300 mm integration studies
- Mechanical exfoliation of vapour-transport-grown crystals
- Liquid exfoliation for inks and lubricant additives
Uses, and how close they are
- n-type transistor channels in 300 mm integration studiesprototype
- Light emitters and lasers coupled to photonic cavitieslab
- Lubricant additives (WS2 nanoparticles and nanosheets)deployed
Readiness runs lab → prototype → pilot → deployed.
Open problems
- Why does photoluminescence efficiency vary so widely between CVD monolayers, and which defects cause the non-radiative losses?
- Can interlayer excitons in WS2-based heterobilayers be used for room-temperature excitonic devices?
- Can WS2 transistors reach the device-to-device uniformity needed for integration at scale?
Going deeper
Short notes for specialists. Choose a lens in the header and yours comes first.
Tungsten’s large spin–orbit coupling reverses the conduction-band spin ordering relative to MoS2 and makes the lowest exciton spin-dark, so optical models must include SOC in both bands. GW–BSE with realistic substrate screening is needed for the ~0.3 eV binding energy; a Rytova–Keldysh potential gives a good effective description of the exciton series.
Identify monolayers by PL near 2.0 eV and Raman: the overlapping 2LA(M)/E′ feature near 350–356 cm−1 and A′1 near 418 cm−1. At 532 nm excitation the 2LA(M) mode is resonantly enhanced, which distorts intensity ratios compared with MoS2.
Evaluated alongside MoS2 as an n-type channel in industrial 2D transistor programmes; tungsten precursors are already familiar in fabs. Contact resistance and dielectric integration are the shared bottlenecks.
In the research tracks
Theory frontiers
Readiness assessments
Recent news
The newest items tagged WS2, from the news feed updated 5 Oct 2026.
Layer-by-layer growth of highly aligned MoS2 nanoribbon arrays
One-dimensional transition metal dichalcogenides (TMD) nanoribbons (NRs) offer a promising route to aggressive channel-width scaling in nanoscale transistors. However, controlling their layer number, a key determinant of device performance, has remained elusive. Here, we demonstrate a chemical vapor deposition (CVD)…
Multi-Branch Transport in a Back-gated WS2 Transistor at Deep-Cryogenic Temperature
Two-dimensional materials are promising candidates for electronic applications beyond the operating limits of conventional semiconductor technologies. Within this class, transition-metal dichalcogenides offer attractive properties for field-effect transistor operation, with tungsten disulphide (WS2) emerging as a…
Electrically switchable one-dimensional quadrupolar excitons in lateral double heterojunctions
Two neighboring lateral interfaces provide a spatial degree of freedom for controlling one-dimensional charge-transfer excitons within a single semiconductor monolayer. We investigate a type-II WS2-MoS2-WS2 double heterojunction using an effective-mass two-particle Hamiltonian with a screened Coulomb interaction. For…
Key references
- Extraordinary room-temperature photoluminescence in triangular WS2 monolayerscited by 1,614doi:10.1021/nl3026357
- Evolution of electronic structure in atomically thin sheets of WS2 and WSe2cited by 2,123doi:10.1021/nn305275h
- Exciton binding energy and nonhydrogenic Rydberg series in monolayer WS2cited by 2,557doi:10.1103/PhysRevLett.113.076802