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<p>This work investigates the influence of structural and material parameters on the performance of lithium tantalate (LiTaO<sub>3</sub>)-based pyroelectric detectors using finite-element simulations. Reducing the thickness of the silicon (Si) diaphragm (underneath the pyroelectric element) from 320 to 10&#xa0;μm significantly improves the detector’s thermal isolation. This leads to a reduction in the thermal time constant (<i>τ</i>) from 94 to 35&#xa0;ms, increase in the current responsivity (<i>R</i><sub>i</sub>) from 0.5670 to 1.686 μA/W, decrease in noise equivalent power (NEP) from 4.32 × 10<sup>–9</sup> to 1.57 × 10<sup>–9</sup> W/√Hz and increase of specific detectivity (<i>D</i><sup>*</sup>) from 4.63 × 10<sup>5</sup> to 1.27 × 10<sup>6</sup>&#xa0;m√Hz/W. After examining the effect of different electrode materials (Au, Pt, Mo, Pd, and Al) Au and Pt were found to perform comparatively better, with <i>R</i><sub>i</sub> values of ~ 3.34 and 3.36 μA/W and <i>D</i>* values of 1.36 × 10<sup>6</sup> and 1.37 × 10<sup>6</sup>&#xa0;m√Hz/W, respectively. Further improvements are achieved by reducing the LiTaO<sub>3</sub> thickness from 100 to 5&#xa0;μm, resulting in lower thermal time constants (~ 21&#xa0;ms) and an increased <i>R</i><sub>i</sub> (up to ~ 7.3 μA/W). Although Au offers a slightly better thermal response at reduced active-layer thicknesses, it was chosen as the electrode material primarily for its ease of patterning and compatibility with standard microfabrication processes compared to Pt. Finally, variations in top electrode thickness from 150 to 50&#xa0;nm, minimizes the detector thermal mass, which improves thermal time constant from 60 to 47&#xa0;ms.</p>

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Finite element thermoelectric assessment of LiTaO3-based pyroelectric MEMS detectors: impact of electrode materials and structural design variations

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Aditi Joshi,
  • Pankaj B. Agarwal

摘要

This work investigates the influence of structural and material parameters on the performance of lithium tantalate (LiTaO3)-based pyroelectric detectors using finite-element simulations. Reducing the thickness of the silicon (Si) diaphragm (underneath the pyroelectric element) from 320 to 10 μm significantly improves the detector’s thermal isolation. This leads to a reduction in the thermal time constant (τ) from 94 to 35 ms, increase in the current responsivity (Ri) from 0.5670 to 1.686 μA/W, decrease in noise equivalent power (NEP) from 4.32 × 10–9 to 1.57 × 10–9 W/√Hz and increase of specific detectivity (D*) from 4.63 × 105 to 1.27 × 106 m√Hz/W. After examining the effect of different electrode materials (Au, Pt, Mo, Pd, and Al) Au and Pt were found to perform comparatively better, with Ri values of ~ 3.34 and 3.36 μA/W and D* values of 1.36 × 106 and 1.37 × 106 m√Hz/W, respectively. Further improvements are achieved by reducing the LiTaO3 thickness from 100 to 5 μm, resulting in lower thermal time constants (~ 21 ms) and an increased Ri (up to ~ 7.3 μA/W). Although Au offers a slightly better thermal response at reduced active-layer thicknesses, it was chosen as the electrode material primarily for its ease of patterning and compatibility with standard microfabrication processes compared to Pt. Finally, variations in top electrode thickness from 150 to 50 nm, minimizes the detector thermal mass, which improves thermal time constant from 60 to 47 ms.