Chemical Vapor Deposition of Rhenium Disulfide Nanoflowers: Effects of Water-Vapor, Substrate Preparation and Post-Growth Treatments.

Rhenium Disulfide is a layered Transition Metal Dichalcogenide (TMD) that exhibits a direct bandgap and potential applications in photosensors, catalysis, and biomedicine. In this work, we study the role of water-vapor during the growth of Rhenium Disulfide via chemical vapor deposition (CVD); rhenium pentachloride and sulfur powder were used as the metal and chalcogen sources, respectively. The introduction of water-vapor during the CVD growth increases the yield and the crystal quality of the samples which resulted in high-density free-standing ReS2 nanoflowers. The presence of small amounts of chalcogen powder on the substrates, before the growth, also increases the yield via creation of additional nucleation centers. Raman and Photoluminescence (PL) spectroscopies were used to characterize the samples, and a laser power-dependent study is presented. After growth, the ReS2 nanoflowers were exposed to a UV treatment in different reactive atmospheres to passivate and/or chemically dope ReS₂. The effect of the post-growth treatments on the PL yield as a function of number of layers is also discussed in this work.