Synthesis and Characterization of Ultrathin FeTe₂ Nanocrystals

Ultrathin crystals including monolayers have been reported for various transition-metal dichalcogenides (TMDCs) with van der Waals bonds in the crystal structure. Herein, we report a detailed synthesis procedure and characterization of ultrathin iron ditelluride crystals. This material crystallizes in an orthorhombic marcasite Pnnm crystal structure whose bonding is dominantly covalent and without loosely connected van der Waals (vdW) bonds, making monolayer FeTe₂ synthesis less straightforward than other TMDC monolayer syntheses. The chemical vapor deposition synthesis process described is simple, effective, and results in a range of crystal thicknesses from approximately 400 nm down to the FeTe₂ monolayer.