Spectrally Selective Photocapacitance Modulation in Plasmonic Nanochannels for Infrared Imaging.
Spectrally Selective Photocapacitance Modulation in Plasmonic Nanochannels for Infrared Imaging.
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DOI：
10.1021/acs.nanolett.6b00326
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发表时间：
2016-04
期刊：
影响因子：
10.8
通讯作者：
Y. Ho;Li-Chung Huang;J. Delaunay
中科院分区：
文献类型：
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作者：
Y. Ho;Li-Chung Huang;J. Delaunay
亚波长等离子体结构的光学响应可以用于监测其物理、化学和生物环境中的微小变化，具有高性能的传感。在远场中的光学响应由等离子体共振的近场性质决定。通过控制结构的形状和使用谐振腔，可以获得尖锐的可调谐谐振。然而，芯片上的等离子体结构的微集成是困难的，因为在远场读出。因此，形成电子微电路并直接监测近场变化的结构将是更期望的。在这里，我们报告的电子可读的光电容器的基础上的等离子体纳米通道结构具有高光谱分辨率和大的调制能力。该结构由金属U型腔和半导体通道组成，用于将光聚焦和限制在半导体-金属界面处。在这些界面处，光被有效地转换成改变结构的电阻抗的光生载流子。响应于光的结构的电容调制产生大于10（3）的明暗对比度。在相同的带宽下，利用3 k Ω的电抗变化量，获得了带宽为16 nm、调制深度为6%的反射谱。这种光电电容器的设计提供了一种实用的手段，监测近场引起的变化，因此可以部署在像素阵列的图像传感器的小型化光谱应用。
The optical response of subwavelength plasmonic structures can be used to monitor minute changes in their physical, chemical, and biological environments with high performance for sensing. The optical response in the far field is governed by the near-field properties of plasmon resonances. Sharp, tunable resonances can be obtained by controlling the shape of the structure and by using resonant cavities. However, microintegration of plasmonic structures on chips is difficult because of the readout in the far field. As such, structures that form an electrical microcircuit and directly monitor the near-field variation would be more desirable. Here, we report on an electronically readable photocapacitor based on a plasmonic nanochannel structure with high spectral resolution and a large modulation capability. The structure consists of metallic U-cavities and semiconductor channels, which are used to focus and confine light at the semiconductor-metal interfaces. At these interfaces, light is efficiently converted into photocarriers that change the electrical impedance of the structure. The capacitance modulation of the structure in response to light produces a light-to-dark contrast ratio larger than 10(3). A reflectance spectrum with a bandwidth of 16 nm and a 6% modulation depth is detected using a reactance variation of 3 kΩ with the same bandwidth. This photocapacitor design offers a practical means of monitoring changes induced by the near field and thus could be deployed in pixel arrays of image sensors for miniaturized spectroscopic applications.