Tellurium pieces

Transition metal chalcogenides were synthesised in a hot-wall quartz tube reactor under low-pressure conditions. The chamber was flushed three times with argon (Ar), and the samples were subsequently heated to 850 °C under 100 sccm Ar. The samples were annealed at this temperature for 30–60 min, and growth was subsequently carried out for 10–15 min by exposing the samples to volatised chalcogen X vapours. The vapours were generated by heating solid chalcogen precursors situated upstream from the samples: ~110 °C for sulphur (sulphur flakes; Sigma Aldrich), ~220 °C for selenium (selenium pellets; Sigma Aldrich), and ~420 °C for tellurium (tellurium pieces; Sigma Aldrich). After growth, the samples were naturally cooled to room temperature under 100 sccm Ar flow. Synthesis of continuous MoS₂ films for electrical device measurements was achieved by increasing the growth temperature to 950 °C.
Identical processing conditions were used to synthesise transition metal nitrides in a cold-wall reactor (AIXTRON Black Magic), except that the entire process was done under 100 sccm H₂ flow instead of argon in order to mitigate surface oxidation of the alloys. The growth of nitrides was performed by introducing 5 sccm NH₃ into the chamber for 5 min The samples were then naturally cooled down to room temperature under 100 sccm H₂.

TaIrTe₄ single crystals were prepared by solid-state reaction using tellurium as flux. Tellurium pieces (99.999%), tantalum powder (99.99%) and iridium powder (99.999%) were purchased from Sigma-Aldrich and were loaded (at an atomic ratio of Te:Ta : Ir = 12 : 1 : 1) into a quartz tube, which was flame sealed under a high vacuum of 10⁻⁶ torr. The quartz tube was placed in the tube furnace, slowly heated to 1000°C and left there for 100 h, before being allowed to cool to 600°C at a rate of 0.8°C h^–1, then cool further to room temperature. At the end, shiny and needle-like TaIrTe₄ single crystals were obtained from the product.