Amani Ouadah

Institute of Optics and Precision Mechanics, Algeria

Title: Elaboration and Characterization of Fe₂O₃ Thin Films

---

Biography

She is an emerging professional in Applied Optics and Instrumentation, with a Master’s degree in Applied Optics and Instrumentation from Ferhat Abbas University – Sétif 1, Algeria. Her academic experience includes thin-film fabrication and characterization, optical sensing, instrumentation, and laser-based measurement systems. She also developed an innovative wearable alert system designed to support deaf and hard-of-hearing individuals through vibration and light-based notifications. Her interests include optical instrumentation, sensor technology, thin-film materials, and innovative optical solutions. She is passionate about applying optics and emerging technologies to practical real-world challenges.

Abstract

Iron oxide (Fe?O?) thin films have attracted considerable interest for optical and functional applications due to their optical properties, thermal stability, low cost, natural abundance, and relatively low toxicity. In this work, Fe?O? thin films were elaborated by the sol–gel dip-coating technique using iron nitrate nonahydrate (Fe(NO?)?·9H?O) as a precursor. The precursor solution was prepared using ethanol and distilled water and stirred at 70 °C for 2 h. Thin films were deposited on glass and fluorine-doped tin oxide (FTO) substrates using controlled immersion and withdrawal conditions, with 20 deposited layers. The films were dried at 200 °C after each deposition and subsequently annealed at temperatures ranging from 300 to 700 °C.

The structural, optical, thickness, and surface morphological properties of the prepared films were investigated using X-ray diffraction (XRD), UV–visible spectroscopy, profilometry, and atomic force microscopy (AFM). XRD analysis confirmed the formation of rhombohedral ?-Fe?O?, with a crystallite size of approximately 75.9 nm and a micro-strain of 0.351. Optical measurements showed strong absorption in the UV–visible region and high transparency toward the near-infrared region. The optical band gap was found to vary from 2.03 eV for films deposited on glass to 1.95 eV for those deposited on FTO, demonstrating the influence of the substrate on the optical response. AFM characterization further revealed a significant difference in surface morphology, with FTO providing a much smoother surface, characterized by an RMS roughness of 0.440 nm compared with 8.648 nm for glass.

These results demonstrate that substrate selection provides an effective means of tuning the structural, optical, and morphological properties of Fe?O? thin films for potential functional optical applications.