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<p>Metal oxide semiconductors are widely studied for gas sensing applications. Among them, hematite (α-Fe₂O₃) is a promising material due to its stability and sensitivity. Controlling its morphology and thickness is crucial for optimizing sensor performance. This work aims to synthesize α-Fe₂O₃ thin films via a sol-gel spin coating technique and investigate the effect of film thickness on their structural, morphological, and alcohol vapor sensing properties. Their crystal structure and surface morphology were characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The sensing performance towards various alcohol vapors (methanol, ethanol, 2-propanol, and n-butanol) was evaluated across a temperature range of 200–320&#xa0;°C. The synthesized films exhibited the characteristic rhombohedral structure of α-Fe₂O₃. Gas sensing tests revealed a pronounced selectivity toward methanol over other tested alcohols. Additionally, the 90&#xa0;nm thick film displayed significantly higher sensitivity compared to the 140&#xa0;nm film. AFM analysis linked this enhancement to its smaller grain size and increased surface roughness, which provides a larger effective surface area for gas interaction. The findings confirm that α-Fe₂O₃ thin films derived by the sol-gel spin coating technique can be considered as a methanol sensor due to high and fast response, low detection limit, and reliable performance.</p>

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Alcohol sensing properties of α-Fe2O3thin films derived by sol-gel spin coating technique

  • 期刊论文

  • 发表日期：

    2026年2月2日

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  • K. Khojier,
  • S. Goudarzi,
  • M. Gholami

摘要

Metal oxide semiconductors are widely studied for gas sensing applications. Among them, hematite (α-Fe₂O₃) is a promising material due to its stability and sensitivity. Controlling its morphology and thickness is crucial for optimizing sensor performance. This work aims to synthesize α-Fe₂O₃ thin films via a sol-gel spin coating technique and investigate the effect of film thickness on their structural, morphological, and alcohol vapor sensing properties. Their crystal structure and surface morphology were characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The sensing performance towards various alcohol vapors (methanol, ethanol, 2-propanol, and n-butanol) was evaluated across a temperature range of 200–320 °C. The synthesized films exhibited the characteristic rhombohedral structure of α-Fe₂O₃. Gas sensing tests revealed a pronounced selectivity toward methanol over other tested alcohols. Additionally, the 90 nm thick film displayed significantly higher sensitivity compared to the 140 nm film. AFM analysis linked this enhancement to its smaller grain size and increased surface roughness, which provides a larger effective surface area for gas interaction. The findings confirm that α-Fe₂O₃ thin films derived by the sol-gel spin coating technique can be considered as a methanol sensor due to high and fast response, low detection limit, and reliable performance.