Enhanced spectroscopic gas sensors using in-situ grown carbon nanotubes
Enhanced spectroscopic gas sensors using in-situ grown carbon nanotubes
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DOI：
10.1063/1.4921170
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发表时间：
2015-05-11
影响因子：
4
通讯作者：
Milne, W. I.
中科院分区：
文献类型：
--
作者：
De Luca, A.;Cole, M. T.;Milne, W. I.
在这封信中，我们提出了一个完全互补的金属氧化物半导体（CMOS）兼容的微机电系统热电堆红外（IR）探测器采用垂直排列的多壁碳纳米管（CNT）作为一种先进的纳米工程辐射吸收材料。该检测器是使用商业绝缘体上硅（SOI）工艺与钨金属化，包括硅热电堆和钨电阻微加热器，都嵌入在由深反应离子蚀刻后的CMOS工艺形成的电介质膜。通过直接热化学气相沉积，使用集成的微加热器作为微反应器，实现了在装置上的原位CNT生长。通过扫描电子显微镜、透射电子显微镜和拉曼光谱验证CNT吸收层的生长。通过比较CNT涂覆的热电堆与未涂覆的热电堆来评估纳米结构的广告层的功能效果。傅里叶变换红外光谱表明，辐射吸收性能的碳纳米管adlayer显着增强的吸收率，与未涂覆的热电堆相比，在整个红外光谱（3 μ m-15.5 μ m）。这导致在CO2非色散IR气体传感器系统中检测到的红外信号（4.26 μ m）放大四倍。CNT层的存在被证明不会降低未涂覆器件的鲁棒性，而检测器的50%调制深度仅略微降低1.5 Hz。此外，我们发现，50%归一化的吸收角分布随后被准直了8度。我们的研究结果表明，基于CNT的SOI CMOS红外传感器的低成本的空气质量监测的可行性。(C)2015 AIP Publishing LLC.
In this letter, we present a fully complementary-metal-oxide-semiconductor (CMOS) compatible microelectromechanical system thermopile infrared (IR) detector employing vertically aligned multi-walled carbon nanotubes (CNT) as an advanced nano-engineered radiation absorbing material. The detector was fabricated using a commercial silicon-on-insulator (SOI) process with tungsten metallization, comprising a silicon thermopile and a tungsten resistive micro-heater, both embedded within a dielectric membrane formed by a deep-reactive ion etch following CMOS processing. In-situ CNT growth on the device was achieved by direct thermal chemical vapour deposition using the integrated micro-heater as a micro-reactor. The growth of the CNT absorption layer was verified through scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The functional effects of the nanostructured ad-layer were assessed by comparing CNT-coated thermopiles to uncoated thermopiles. Fourier transform IR spectroscopy showed that the radiation absorbing properties of the CNT adlayer significantly enhanced the absorptivity, compared with the uncoated thermopile, across the IR spectrum (3 mu m-15.5 mu m). This led to a four-fold amplification of the detected infrared signal (4.26 mu m) in a CO2 non-dispersive-IR gas sensor system. The presence of the CNT layer was shown not to degrade the robustness of the uncoated devices, whilst the 50% modulation depth of the detector was only marginally reduced by 1.5 Hz. Moreover, we find that the 50% normalized absorption angular profile is subsequently more collimated by 8 degrees. Our results demonstrate the viability of a CNT-based SOI CMOS IR sensor for low cost air quality monitoring. (C) 2015 AIP Publishing LLC.