Topographical investigation of rhenium oxide thin films grown via direct chemical vapor deposition

Nanostructured transition metal oxides (TMOs) are important materials, but they are often challenging to grow directly on substrates. In this work, large-area, continuous ReO₃ thin films were successfully synthesized via direct CVD on non-catalytic substrates using NH₄ReO₄ powder as the precursors. The films were characterized by Raman spectroscopy, SEM, EDS, AFM, and XPS. Raman spectroscopy revealed characteristic ReO₃ peaks at 332.52, 886.93, and 956.72 cm⁻¹. EDS confirmed a Re:O atomic ratio of approximately 1:3, while AFM revealed an average film thickness of ∼20 nm. High-resolution XPS demonstrated a predominant Re⁶⁺ oxidation state consistent with ReO₃, although the presence of additional minor ReO_x species cannot be excluded. This direct CVD approach offers a scalable route for the growth of ReO₃ thin-film on various substrates for device integration.