Tailoring Vanadium Oxide Thin Film Structure and Electrical Properties via Pulsed DC and RF Magnetron Sputtering

Vanadium oxide thin films are increasingly explored for electronic, electrochemical, and energy-related applications due to their variable oxidation states and versatile physicochemical properties. This study systematically compares the effects of pulsed DC and RF magnetron sputtering techniques on the structural, morphological, and electrical characteristics of vanadium oxide films deposited on 304 AISI stainless steel substrates. High-purity vanadium target was sputtered in a controlled Ar/O2 environment. X-ray diffraction (XRD) revealed that pulsed DC sputtering favored the formation of monoclinic VO2, while RF sputtering promoted orthorhombic V2O5, indicating a phase transition driven by deposition parameters. The average crystallite size was smaller in pulsed DC films (~10.12 nm) than in RF films (~12.26 nm). X-ray photoelectron spectroscopy (XPS) showed that pulsed DC sputtering produced films with more stable V4+/V5+ ratios and controlled stoichiometry. In contrast, RF-deposited films exhibited higher oxidation states and greater surface contamination due to porosity. Fourier transform infrared (FTIR) spectra confirmed these phase distinctions by identifying vibrational modes corresponding to VO2-rich and V2O5-rich compositions. Scanning electron microscopy (SEM) revealed that pulsed DC film was thinner, denser, and smoother, while RF film was thicker with a porous nanostructure. Electrical measurements showed higher conductivity in pulsed DC films (~4.04 × 10-4 S/cm) than in RF films (~3.22 × 10-4 S/cm). These findings highlight the critical role of deposition technique in tailoring vanadium oxide thin films for advanced smart devices and energy systems.