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<p>Gold-coated silicon substrates have become crucial for advancing optoelectronic devices and nanostructures due to their enhanced properties. This study employs an integrated approach combining the finite-difference time-domain (FDTD) method with the two-temperature model-molecular dynamics (TTM-MD) simulation to investigate ultrafast laser ablation. Simulations were performed on Si substrates coated with varying Au coating thicknesses (0, 20, 35&#xa0;nm) using a 100-fs, 1030&#xa0;nm-laser at fluences of 50 and 100&#xa0;mJ/cm<sup>2</sup> over a 100-ps duration. We analyzed the temporal evolution of density, potential energy, and pressure distribution to reveal the effects of both coating thickness and laser fluence on the ablation mechanism. The results show that the 20-nm and 35-nm Au coatings reduce energy absorption in the Si substrate by 35% and 66%, respectively, compared to bare Si. The Au layer acts as a protective barrier by partially absorbing and reflecting laser energy, which induces localized heating and reduces atomic displacement and potential energy in the underlying Si. The absorbed energy generates mechanical stress within the Au layer, which confines tensile stress transfer to the Si and suppresses microfracturing. Although higher fluence enhances ablation efficiency, it concurrently increases the risk of Si substrate subsurface cracking. This work provides quantitative insights for optimizing laser processing parameters, including laser fluence and coating thickness, for precise nanostructure fabrication.</p> Graphical Abstract <p></p>

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Atomistic Insights into the Laser–Material Interaction in Gold-Coated Silicon: A TTM-MD Approach

  • 期刊论文

  • 发表日期：

    2026年1月16日

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  • Dongwei Li,
  • Ziyang Xie,
  • Haoyu Shi,
  • Jinrui Xiao

摘要

Gold-coated silicon substrates have become crucial for advancing optoelectronic devices and nanostructures due to their enhanced properties. This study employs an integrated approach combining the finite-difference time-domain (FDTD) method with the two-temperature model-molecular dynamics (TTM-MD) simulation to investigate ultrafast laser ablation. Simulations were performed on Si substrates coated with varying Au coating thicknesses (0, 20, 35 nm) using a 100-fs, 1030 nm-laser at fluences of 50 and 100 mJ/cm2 over a 100-ps duration. We analyzed the temporal evolution of density, potential energy, and pressure distribution to reveal the effects of both coating thickness and laser fluence on the ablation mechanism. The results show that the 20-nm and 35-nm Au coatings reduce energy absorption in the Si substrate by 35% and 66%, respectively, compared to bare Si. The Au layer acts as a protective barrier by partially absorbing and reflecting laser energy, which induces localized heating and reduces atomic displacement and potential energy in the underlying Si. The absorbed energy generates mechanical stress within the Au layer, which confines tensile stress transfer to the Si and suppresses microfracturing. Although higher fluence enhances ablation efficiency, it concurrently increases the risk of Si substrate subsurface cracking. This work provides quantitative insights for optimizing laser processing parameters, including laser fluence and coating thickness, for precise nanostructure fabrication.

Graphical Abstract