The Effect of Argon:Oxygen Gas Mixture on DC-Sputtering Deposition Characterization of Synthesis SiO₂ Nanoparticles

In this work, nanostructured silicon dioxide (SiO₂) thin films were deposited on glass substrates using a DC reactive magnetron sputtering technique. A gaseous mixture of argon and oxygen at different mixing ratios was used to synthesize SiO₂ nanoparticles. Following the extraction of the SiO₂ powder from the glass substrate, we analyzed it to study its structural, morphological, and optical characteristics. X-ray diffraction (XRD) revealed a transition from amorphous to partially crystalline phases as the oxygen ratio increased, indicating enhanced crystallinity under oxygen-rich conditions. Field emission scanning electron microscopy (FE-SEM) showed that particle size decreased with higher oxygen content, suggesting improved oxidation and limited grain growth. Atomic force microscopy (AFM) indicated smoother surfaces at intermediate gas ratios, with the lowest RMS roughness observed at an Ar:O₂ ratio of 70:30. Optical absorbance measurements demonstrated that the film deposited at a 50:50 ratio exhibited the highest absorbance in the visible range (400-600 nm), making it promising for optoelectronic applications. The results confirm that the Ar:O₂ gas ratio plays a critical role in tuning the structural and optical properties of SiO₂ nanostructured thin films.