p-type WS2 Crystal
More than a decade of growth optimization in chemical vapor transport (CVT) as well as flux growth lead to our flawless WS2 crystals. Our p-type WS2 crystals are doped with Nb atoms at 1E17-5E18cm-3 range. These electronically doped vdW WS2 crystals are treated as gold standards in 2D materials field. WS2 crystals from 2Dsemiconductors are known for its superior valleytronic performance, perfect crystallization, defect free structure, extremely narrow PL bandwidths, clean PL spectra (free of bound exciton shoulders), and high carrier mobility. Thousands of scientific articles have cited us and used these crystals for scientific accuracy and clean signals. Please also see our n- and p-type WS2 crystals doped with Au, Re, Nb, or other transition metal atoms.
Please note that doping into TMDCs greatly reduce the crystallization time (growth speeds), thus electronically doped TMDCs measure smaller than undoped (intrinsic) TMDCs.
Typical characteristics of WS2 crystals from 2Dsemiconductors
Growth method matters> Flux zone or CVT growth method? Contamination of halides and point defects in layered crystals are well known cause for their reduced electronic mobility, reduced anisotropic response, poor e-h recombination, low-PL emission, and lower optical absorption. Flux zone technique is a halide free technique used for synthesizing truly semiconductor grade vdW crystals. This method distinguishes itself from chemical vapor transport (CVT) technique in the following regard: CVT is a quick (~2 weeks) growth method but exhibits poor crystalline quality and the defect concentration reaches to 1E11 to 1E12 cm-2 range. In contrast, flux method takes long (~3 months) growth time, but ensures slow crystallization for perfect atomic structuring, and impurity free crystal growth with defect concentration as low as 1E9 - 1E10 cm-2. During check out just state which type of growth process is preferred. Unless otherwise stated, 2Dsemiconductors ships Flux zone crystals as a default choice.
XRD data collected from WS2 crystals
Raman spectrum collected from WS2 monolayers
PL spectrum collected from monolayer WS2 on SiO2/Si substrates
SIMS purity datasets collected from WS2 crystals
HRTEM images collected from WS2 crystals
Partial List of Published Articles from This Product
Summary: Publications from MIT, Washington, MIT, Berkeley, Stanford, and Princeton teams at top journals like Nature Nanotechnology, Nano Letters, and Advanced Materials
Control of Exciton Valley Coherence in Transition Metal Dichalcogenide Monolayers, Phys. Rev. Lett. 117, 187401 (2016)
T. Scrace et. al. "Magnetoluminescence and valley polarized state of a two-dimensional electron gas in WS2 monolayers" Nature Nanotechnology 10, 603–607 (2015) doi:10.1038/nnano.2015.78
J. He et. al. "Electron transfer and coupling in graphene–tungsten disulfide van der Waals heterostructures" Nature Communications 5, Article number: 5622 (2014)
Measurement of the optical dielectric function of monolayer transition-metal dichalcogenides: MoS2, MoSe2, WS2, and WSe2, Yilei Li, Alexey Chernikov, Xian Zhang, Albert Rigosi, Heather M. Hill, Arend M. van der Zande, Daniel A. Chenet, En-Min Shih, James Hone, and Tony F. Heinz; Phys. Rev. B 90, 205422 (2014)
UT Austin - A. P. Nayak et. al. "Pressure-Modulated Conductivity, carrier Density, and Mobility of Multilayered Tungsten Disulfide" ACS Nano 10.1021/acsnano.5b03295
N. Peimyoo et. al. Nonblinking, Intense Two-Dimensional Light Emitter: Monolayer WS2 Triangles ACS Nano, 2013, 7 (12), pp 10985–10994
Manish Chhowalla, "Two-dimensional semiconductors for transistors" Nature Reviews Materials 1, Article number: 16052 (2016) doi:10.1038/natrevmats.2016.52
Tongay et. al. "Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged, and free excitons" Scientific Reports 3, Article number: 2657 (2013)
X Li et al. "Determining layer number of twodimensional flakes of transition-metal dichalcogenides by the Raman intensity from substrates" Nanotechnology 27 (2016) 145704