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<p>Fe<sub>3</sub>O<sub>4</sub>@ZnO core–shell nanoparticles were synthesized using an environmentally benign, surfactant-free pulsed laser ablation in liquid (PLAL) method and deposited onto porous silicon (PS) substrates prepared by photoelectrochemical etching. The influence of synthesis laser pulse energies of 400, 600, and 800 mJ on the structural, morphological, optical, and photoelectrical properties of the Fe<sub>3</sub>O<sub>4</sub>@ZnO/PS heterostructures was systematically investigated using XRD, SEM, TEM, UV–Vis absorption, photoluminescence (PL), and electrical measurements. XRD analysis confirmed the coexistence of cubic Fe<sub>3</sub>O<sub>4</sub> and hexagonal wurtzite ZnO phases, while TEM observations verified the formation of core–shell nanoparticles with average sizes of approximately 19, 30, and 70 nm depending on the laser energy. UV–Vis/Tauc analysis showed that the optical band gap decreased from 3.00 to 2.87 eV as the laser pulse energy increased, indicating a laser-energy-dependent modification of the optical properties. PL spectra recorded from the Fe<sub>3</sub>O<sub>4</sub>@ZnO/PS samples exhibited emission peaks in the range of 3.38–3.45 eV, which are attributed to ZnO-related near-band-edge and defect/interface-assisted emission rather than direct band gap values. The reduction in PL intensity at higher synthesis energy suggests improved charge separation or reduced relative radiative recombination. Electrical measurements revealed enhanced current density for Fe<sub>3</sub>O<sub>4</sub>@ZnO/PS heterostructures compared with bare PS, with the 800 mJ sample showing the best photoelectrical response. The fabricated photodetectors exhibited improved responsivity up to 0.1 A/W and enhanced detectivity across the visible-to-near-infrared region. These results demonstrate that controlling the PLAL laser pulse energy is an effective strategy for tuning Fe<sub>3</sub>O<sub>4</sub>@ZnO core–shell nanostructures for broadband optoelectronic and photodetector applications.</p>

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Structural, optical, and electronic characterization of Fe3O4@ZnO core–shell nanostructures synthesized by laser ablation

  • 期刊论文

  • 发表日期：

    2026年5月25日

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  • Salah M. Abdul Aziz,
  • Hayder Hasan Ali,
  • Ahmed B. Taha,
  • Mohammed W. Muayad,
  • Chra N. Salih,
  • Uday M. Nayef

摘要

Fe3O4@ZnO core–shell nanoparticles were synthesized using an environmentally benign, surfactant-free pulsed laser ablation in liquid (PLAL) method and deposited onto porous silicon (PS) substrates prepared by photoelectrochemical etching. The influence of synthesis laser pulse energies of 400, 600, and 800 mJ on the structural, morphological, optical, and photoelectrical properties of the Fe3O4@ZnO/PS heterostructures was systematically investigated using XRD, SEM, TEM, UV–Vis absorption, photoluminescence (PL), and electrical measurements. XRD analysis confirmed the coexistence of cubic Fe3O4 and hexagonal wurtzite ZnO phases, while TEM observations verified the formation of core–shell nanoparticles with average sizes of approximately 19, 30, and 70 nm depending on the laser energy. UV–Vis/Tauc analysis showed that the optical band gap decreased from 3.00 to 2.87 eV as the laser pulse energy increased, indicating a laser-energy-dependent modification of the optical properties. PL spectra recorded from the Fe3O4@ZnO/PS samples exhibited emission peaks in the range of 3.38–3.45 eV, which are attributed to ZnO-related near-band-edge and defect/interface-assisted emission rather than direct band gap values. The reduction in PL intensity at higher synthesis energy suggests improved charge separation or reduced relative radiative recombination. Electrical measurements revealed enhanced current density for Fe3O4@ZnO/PS heterostructures compared with bare PS, with the 800 mJ sample showing the best photoelectrical response. The fabricated photodetectors exhibited improved responsivity up to 0.1 A/W and enhanced detectivity across the visible-to-near-infrared region. These results demonstrate that controlling the PLAL laser pulse energy is an effective strategy for tuning Fe3O4@ZnO core–shell nanostructures for broadband optoelectronic and photodetector applications.