Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi 184-8588, Japan.
National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei-shi 184-8795, Japan.
Sensors (Basel). 2022 Jul 7;22(14):5109. doi: 10.3390/s22145109.
Terahertz (THz) electromagnetic waves are attractive for use in nondestructive and biocompatible sensing applications. Thermal sensors are widely used for THz detection owing to the small photon energies of THz radiation, where this requires materials with low thermal conductivity and a small heat capacity to ensure the sensitive and fast operation of the sensors. In this study, we investigated the thermal and optical properties of porous nanomesh structures for sensitive THz bolometric detection. Nanometer (nm)-scale hole array structures were formed on gallium arsenide (GaAs) microelectromechanical system (MEMS) beams to improve their thermal properties. The thermal conductance of the porous MEMS beams was obtained by measuring their thermal bandwidths; it was found to decrease by as much as ~90% when the porosity () of the porous nanostructure was increased to ~0.69. We also measured the THz absorptance of the porous hole array structure. The results show that although the porous nanostructure has a much smaller area than the bulk material, it maintained a high coefficient of THz absorptance because the featured size was much smaller than the THz wavelength. The measured absorptance agreed well with that calculated by using the Drude model. These results demonstrate that the porous nanomesh structure is promising for developing highly sensitive THz thermal sensors.
太赫兹（THz）电磁波在无损和生物兼容的传感应用中很有吸引力。由于太赫兹辐射的光子能量较小，热传感器被广泛用于太赫兹检测，这就需要具有低导热率和小热容的材料，以确保传感器的灵敏和快速运行。在这项研究中，我们研究了用于灵敏太赫兹量热探测的多孔纳米网结构的热学和光学性质。在砷化镓（GaAs）微机电系统（MEMS）梁上形成纳米级孔阵列结构，以改善其热性能。通过测量其热带宽来获得多孔 MEMS 梁的热导，当多孔纳米结构的孔隙率（）增加到约 0.69 时，热导降低了约 90%。我们还测量了多孔孔阵列结构的太赫兹吸收率。结果表明，尽管多孔纳米结构的面积比体材料小得多，但由于特征尺寸远小于太赫兹波长，它保持了较高的太赫兹吸收率。测量的吸收率与使用 Drude 模型计算的吸收率吻合较好。这些结果表明，多孔纳米网结构有望开发出高灵敏度的太赫兹热传感器。
