Ding Hao, Wu Shaolong, Zhang Cheng, Li Liujing, Sun Qingxin, Zhou Luwei, Li Xiaofeng
Opt Express. 2020 Mar 2;28(5):6511-6520. doi: 10.1364/OE.387339.
Due to the strongly concentrated electromagnetic field and the ability to detect the below-bandgap photon energies, surface-plasmon-based photodetections have attracted considerable attention. However, the manipulation of plasmonic resonance is complicated with a high cost in fabrication; moreover, the performance of hot-electron photodetectors is generally unsatisfactorily low. Here, we demonstrated that a tunable absorption can be realized by using the nanohole patterned metal-spacer-metal (MSM) structure, which can be wafer-scale fabricated by the nanosphere lithography technology. The angle- and polarization-insensitive absorption is realized under the excitation of the gap-mode plasmons, which can be facilely manipulated in the near-infrared band by varying the thicknesses and material of the spacer as well as the diameter and period of the nanohole arrays. An asymmetrically bended electrical system is proposed to efficiently convert the highly absorbed photon energies into the photocurrent. Results show that the responsivity of the prepared MSM structure can be up to ∼2.82 mA/W at the wavelength of 1150 nm.
由于强聚焦电磁场以及检测低于带隙光子能量的能力，基于表面等离子体激元的光电探测器引起了广泛关注。然而，等离子体共振的操控较为复杂，制造成本高昂；此外，热电子光电探测器的性能通常低得不尽人意。在此，我们证明了通过使用纳米孔图案化的金属-间隔层-金属（MSM）结构可以实现可调谐吸收，该结构可通过纳米球光刻技术进行晶圆级制造。在间隙模式等离子体激元的激发下实现了角度和偏振不敏感吸收，通过改变间隔层的厚度和材料以及纳米孔阵列的直径和周期，可以在近红外波段轻松操控这种吸收。提出了一种不对称弯曲的电气系统，以有效地将高吸收光子能量转换为光电流。结果表明，所制备的MSM结构在1150 nm波长处的响应度可达约2.82 mA/W。
