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<p>Germanium oxide (GeO<sub>2</sub>) thin films were successfully deposited onto silicon (Si) (111) substrates using Pulsed Laser Deposition (PLD) for use as gas sensors for NH<sub>3</sub> and NO<sub>2</sub>. Films were prepared at varying laser energies (200, 250, 300, and 350 mJ). X-ray diffraction (XRD) confirmed a hexagonal crystal structure. The intensity of the dominant (101) peak increased significantly with higher laser energy, indicating enhanced crystallinity (crystallite size grew from 24.9 nm to 29.2 nm). Morphological analyses showed that increasing laser energy from 200 to 350 mJ resulted in higher surface roughness (13.1 nm to 20.5 nm) but a substantial decrease in particle size (58.7 nm to 22.2 nm). Optically, the band gap (Eg) increased from 3.55 eV to 3.65 eV with rising laser energy, establishing a direct correlation between deposition parameters and the electronic structure. The film prepared at 350 mJ exhibited the optimal combination of structural and morphological properties (highest crystallinity and roughest surface) and was therefore selected for initial gas sensing measurements. Gas sensing confirmed that the GeO<sub>2</sub> /Si sensors showed their highest overall sensitivity to both NH<sub>3</sub> and NO<sub>2</sub> at an optimal operating temperature of 200 °C. However, the 350 mJ film exhibited the highest individual gas sensitivities: 10.5% for NH<sub>3</sub> and 36.8% for NO<sub>2</sub>. This superior response was attributed to its specific particle size distribution, which maximizes the active area for gas interaction. These results underscore the critical role of laser energy control in tailoring GeO<sub>2</sub> film properties for specific sensing applications.</p>

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Pulsed Laser Deposition of GeO2​/Si Thin Films: Tailoring Gas Sensing Performance for NH3​ and NO2​ through Laser Energy Control

  • 期刊论文

  • 发表日期：

    2025年12月23日

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  • Mohammed N. Gaser,
  • Hossain M. Moghaddam,
  • Mahdi M. Mutter

摘要

Germanium oxide (GeO2) thin films were successfully deposited onto silicon (Si) (111) substrates using Pulsed Laser Deposition (PLD) for use as gas sensors for NH3 and NO2. Films were prepared at varying laser energies (200, 250, 300, and 350 mJ). X-ray diffraction (XRD) confirmed a hexagonal crystal structure. The intensity of the dominant (101) peak increased significantly with higher laser energy, indicating enhanced crystallinity (crystallite size grew from 24.9 nm to 29.2 nm). Morphological analyses showed that increasing laser energy from 200 to 350 mJ resulted in higher surface roughness (13.1 nm to 20.5 nm) but a substantial decrease in particle size (58.7 nm to 22.2 nm). Optically, the band gap (Eg) increased from 3.55 eV to 3.65 eV with rising laser energy, establishing a direct correlation between deposition parameters and the electronic structure. The film prepared at 350 mJ exhibited the optimal combination of structural and morphological properties (highest crystallinity and roughest surface) and was therefore selected for initial gas sensing measurements. Gas sensing confirmed that the GeO2 /Si sensors showed their highest overall sensitivity to both NH3 and NO2 at an optimal operating temperature of 200 °C. However, the 350 mJ film exhibited the highest individual gas sensitivities: 10.5% for NH3 and 36.8% for NO2. This superior response was attributed to its specific particle size distribution, which maximizes the active area for gas interaction. These results underscore the critical role of laser energy control in tailoring GeO2 film properties for specific sensing applications.