WTe2 is a Type-II Weyl semimetal with carrier density spanning from 1E20-1E21 cm-3. Unlike other sources, our growth involves highly sophisticated float zone technique which allows us to drive out defects intentionally during the growth process to achieve defect free crystals. In our experience, conventional chemical vapor transport (CVT) technique severely introduces defects and impurities into the material, and alters its must desired intrinsic properties. Furthermore, CVT method produces defected crystals which leads to environmental instability. See Figures for characterization results. Our crystals are grown in three (3) months period to achieve environmentally stable, pure, and intrinsic Weyl response crystals. 
Typical characteristics of WTe2 crystals from 2Dsemiconductors USA

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.

Highlights of our WTe2 crystals;
Crystals are grown by float zone technique to achieve defect free and environmentally stable WTe2 crystals. 
Our WTe2 crystals are stable in ambient conditions and no sealing or careful storage conditions needed.
Crystals do not contain any impurities like TeCl4 or Br2 coming from transport agents used in conventional CVT process. 
Each and every single crystal piece is characterized using EDAX, XRD, Raman, and hall measurements to unsure reproducible results with highest accuracy and confidence in crystals.