Lin Albert, Yang Chien-Chih, Parashar Parag, Lin Chien-Yung, Jian Ding Rung, Huang Wei-Ming, Huang Yi-Wen, Fu Sze Ming, Zhong Yan Kai, Tseng Tseung Yuen
Department of Electronics Engineering, National Chiao-Tung University Hsinchu Taiwan 30010
RSC Adv. 2018 Jan 17;8(7):3453-3461. doi: 10.1039/c7ra12113j. eCollection 2018 Jan 16.
Carbon nanotubes (CNTs) possesses decent optical properties and thus can be considered as a candidate for perfect absorbers due to their close-to-air refractive index and minimal extinction. However, weak absorption in porous materials, due to the low extinction coefficients, requires an inevitably thick absorption layer (∼100 μm) for the perfect opaque absorbers. Thus, the requirement of large thicknesses of CNTs prohibits them from being used as miniaturized integrated photonic devices. Here, we propose an electrophoretic deposited (EPD) CNT resonant cavity structure on tantalum (Ta) to enhance optical absorption. Efficient random light scattering along with the resonant cavity structure using Ti/SiO stacking enhances the absorption in our proposed EPD-CNT film while maintaining the total device thickness to <1 μm. The experiment results reveal that the absorption band covers the entire UV-VIS-NIR spectrum ( = 0.3-2.6 μm), using resonant-cavity EPD-CNT design. The EPD deposition process is done at relatively low temperature < 120 °C. We believe that this proposal is very promising for sensing, antenna, and thermophotovoltaics (TPV), in terms of bandwidth, compactness and cost.
碳纳米管（CNTs）具有良好的光学性能，由于其接近空气的折射率和最小的消光，因此可被视为完美吸收体的候选材料。然而，由于消光系数低，多孔材料中的吸收较弱，对于完美的不透明吸收体而言，不可避免地需要较厚的吸收层（约100μm）。因此，对碳纳米管厚度的要求使其无法用作小型化集成光子器件。在此，我们提出在钽（Ta）上采用电泳沉积（EPD）的碳纳米管谐振腔结构来增强光吸收。利用Ti/SiO堆叠的谐振腔结构实现的高效随机光散射增强了我们所提出的EPD-CNT薄膜中的吸收，同时将整个器件的厚度保持在<1μm。实验结果表明，采用谐振腔EPD-CNT设计时，吸收带覆盖了整个紫外-可见-近红外光谱（λ = 0.3 - 2.6μm）。EPD沉积过程在相对较低的温度<120°C下进行。我们认为，就带宽、紧凑性和成本而言，该方案在传感、天线和热光伏（TPV）方面非常有前景。
