Synthesis and characterization of two-dimensional ReS2 flakes grown by chemical vapor deposition on SiO2/Si substrate

Rhenium disulfide (ReS 2 ) flakes were synthesized by chemical vapor deposition (CVD) on SiO 2 /Si substrate using elemental sulfur, with NH 4 ReO 4 and ReO 3 as precursors. Growth was carried out at 600 °C for 10 min under argon gas flow. NH 4 ReO 4 -grown ReS 2 exhibited photoluminescence (PL) emission at 822 nm (1.51 eV), whereas ReO 3 -grown ReS 2 emitted at 809.9 nm (1.53 eV) under the same growth conditions. Both hexagonal and irregularly shaped flakes were obtained, with Raman spectra showing 17–18 Raman-active modes. Atomic force microscopy of a representative CVD-grown flake showed local step heights of approximately 18.5 and 27.5 nm, indicating a multilayer flake with local thickness variation. Optical microscopy showed local variation in flake size and nucleation density across the examined regions. Compared with a commercial ReS 2 reference, the CVD-grown sample showed similar principal photoluminescence and Raman peak positions but a broader PL full width at half maximum, 96.70 and 78.00 nm, respectively.