Controllable growth of large-area monolayer ReS2 flakes by chemical vapor deposition

Two-dimensional (2D) ReS 2 flakes are synthesized by the chemical vapor deposition under atmospheric pressure using Re–Te binary eutectic and sulfur as precursors. The morphologies, crystal structure, phonon vibration modes, chemical states and optical property of the 2D ReS 2 flakes are characterized using optical microscopy, scanning electron microscope, transmission electron microscopy, the Raman spectroscopy, X-ray photoelectron spectroscopy and transmittance spectra. The lateral size of 2D ReS 2 flakes can be tuned via changing the synthesis parameters. The monolayer 2D ReS 2 flakes is single crystal structure. Its maximum lateral size is 30 μm, and optical band gap is 1.42 eV. The absorption coefficient is as large as 10 5 cm −1 , transmittance of 92–98% and refractive index of 1.5–1.3 in the wavelength range from 400 to 800 nm. The effect of synthesis parameters on the morphologies and growth mechanism of 2D ReS 2 flakes are investigated in detail. This is helpful for further application of ReS 2 in electronic and optoelectronic devices.