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首页> 外文期刊>Applied Surface Science >In-plane optical anisotropy and SERS detection efficiency of self-organized gold nanoparticles on silicon nanoripples: Roles of growth angle and postgrowth annealing
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In-plane optical anisotropy and SERS detection efficiency of self-organized gold nanoparticles on silicon nanoripples: Roles of growth angle and postgrowth annealing

机译：自组织金纳米粒子在硅纳米波纹上的面内光学各向异性和SERS检测效率：生长角和生长后退火的作用

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摘要

In this work, we report on substrate morphology-mediated plasmonic anisotropy and surface-enhanced Raman scattering-based molecular detection efficacy of oblique angle grown self-organized gold nanoparticles (Au-NPs) on ultralow energy ion-beam fabricated nanoscale rippled-Si (R-Si) substrates. To study the effect on plasmonic field coupling, the shape of Au-NPs is tuned from elongated to spherical ones by varying the growth angle leading to a change in the interparticle gap. Following this, postgrowth annealing of Au-NP arrays is carried out to change the shape and size of Au-NPs via Ostwald ripening process. The optical anisotropy is measured using generalized ellipsometry, while dielectric functions of Au-NP arrays are calculated using a biaxial layer model by fitting the Jones matrix elements. A stronger plasmonic field coupling becomes evident from the imaginary part of dielectric functions along x- and y-axes which is further supported by finite-difference time-domain (FDTD) simulations. Enormous near-field enhancement between Au-NPs leads to surface-enhanced Raman scattering (SERS)-based detection of an ultralow concentration (10 mu M) of crystal violet dye. Further, FDTD simulation reveals that hotspot formation takes place between Au-NPs due to lesser interparticle gaps along the Au-NP arrays compared to the ones between two adjacent arrays. Thus, Au-NP arrays exhibit in-plane anisotropic optical response. The improved SERS-based detection efficacy of complex molecules is attributed to their enhanced Raman scattering cross-section in the vicinity of these hotspots. This study demonstrates that self-organized AuNP arrays on nanoscale rippled-Si substrates can work as an efficient and longevous SEAS sensor due to the prolonged stability of Au in environmental conditions. This study will pave the way to fabricate plasmonic devices and SERS-based sensing of complex molecules having low Raman scattering cross-sections.
机译：在这项工作中，我们报告了斜向生长的自组织金纳米颗粒（Au-NPs）在超低能离子束制备的纳米级波纹硅（Au-NPs）上的基质形态介导的等离子体各向异性和基于表面增强拉曼散射的分子检测功效。 R-Si）基板。为了研究对等离子体场耦合的影响，通过改变生长角度导致粒子间间隙的变化，将金纳米粒子的形状从拉长的形状调整为球形。此后，进行Au-NP阵列的生长后退火，以通过Ostwald熟化工艺改变Au-NP的形状和尺寸。使用广义椭圆偏振法测量光学各向异性，同时使用双轴层模型通过拟合琼斯矩阵元素来计算Au-NP阵列的介电函数。从沿着x和y轴的介电函数的虚部，可以看出更强的等离子体场耦合，这进一步由有限差分时域（FDTD）模拟来支持。 Au-NP之间的巨大近场增强会导致基于表面增强拉曼散射（SERS）的结晶紫染料超低浓度（10μM）检测。此外，FDTD模拟显示，由于沿Au-NP阵列的粒子间间隙比两个相邻阵列之间的间隙小，因此在Au-NP之间发生了热点形成。因此，Au-NP阵列表现出面内各向异性光学响应。复杂分子基于SERS的检测功效的提高归因于这些热点附近区域拉曼散射截面的增强。这项研究表明，由于金在环境条件下的长期稳定性，纳米波纹硅衬底上的自组织AuNP阵列可以用作高效且使用寿命长的SEAS传感器。这项研究将为制造具有低拉曼散射截面的复杂分子的等离激元器件和基于SERS的传感铺平道路。

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  • 来源
    《Applied Surface Science》 |2020年第may15期|145703.1-145703.11|共11页
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  • 作者单位

    SUNAG Lab Inst Phys Sachivalaya Marg Bhubaneswar 751005 Odisha India|Homi Bhabha Natl Inst Training Sch Complex Mumbai 400 085 Maharashtra India;

    Homi Bhabha Natl Inst Training Sch Complex Mumbai 400 085 Maharashtra India|Facilitiat Ctr Ind Plasma Technol Inst Plasma Res Gandhinagar 382428 Gujarat India;

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  • 正文语种 eng
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  • 关键词

    Au-NP; LSPR; Ellipsometry; SEAS; Crystal violet; Ripples;

    机译：金纳米颗粒;LSPR;椭圆仪海域;结晶紫;涟漪;

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