The only commercially available TlGaTe2 vdW crystals have been synthesized at our facilities through float zone technique. TlGaTe2 semiconductors belong to the thallium chalcogenides family with the chemical formula TlBX2 (where B=In or Ga, X=S, Se or Te). Members of this family have both layered (TlGaSe2, TlGaS2, TlInS2) and chain (TlInSe2, TlInTe2, ) structures. Stacking of the atoms in TlGaSe2, TlGaS2 and TlInS2 layered crystals is arranged in the form of two twisted anionic layers with the weak bonded Tl(+1) cations located in the trigonal cavities between them. Recently, low-temperature rhombohedral ordered
phase of Tl-based III–V–VI2 ternary chalcogenides has been predicted to be topologically nontrivial and a terminated surface with a single Dirac cone has been identified through first-principles calculations (Phys. Rev. Lett. 105, 036404). crystals exhibit anisotropic structural, electronic, and optical properties with the bａnd gap of 1.2 eV.

Properties of layered crystals by 2Dsemiconductors USA