Graphene, a semi-metal with a gapless band structure, has been used in mid-infrared (MIR) photodetectors (PDs) for some time. However, these detectors often suffer from low responsivity due to the intrinsically low absorption and ultra-short carrier lifetime in graphene, large dark current, and low detectivity due to the semi-metallic nature of graphene. Over the past decade, much effort has been devoted to addressing these issues. A variety of metamaterials and related concepts has been employed to improve the detector responsivity by enhancing the graphene absorption and/or the carrier collection efficiency. Here, we provide an overview of the graphene MIR PDs with and without the use of approaches for responsivity enhancement. We focus our attention on the state-of-the-art graphene MIR PDs whose performance is improved by employing metamaterials and related concepts, including band structure engineering, the photogating effect, integration with plasmonic nanostructures and waveguides, the use of asymmetric plasmons, coupled plasmon–phonon polaritons, and small-twist-angle bilayer graphene. We conclude by providing possible directions for further performance improvement of graphene MIR PDs and a discussion on future applications of these detectors.

中文翻译：

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使用超材料和相关概念的基于石墨烯的中红外光电探测器

石墨烯是一种具有无间隙带结构的半金属，在中红外 (MIR) 光电探测器 (PD) 中使用已有一段时间。然而，由于石墨烯固有的低吸收和超短载流子寿命、大暗电流以及石墨烯的半金属性质导致的低探测率，这些探测器通常具有低响应性。在过去的十年中，已经付出了很多努力来解决这些问题。各种超材料和相关概念已被用于通过增强石墨烯吸收和/或载流子收集效率来提高探测器响应度。在这里，我们概述了使用和不使用响应度增强方法的石墨烯 MIR PD。我们将注意力集中在最先进的石墨烯 MIR PD 上，其性能通过采用超材料和相关概念得到改善，包括能带结构工程、光门效应、与等离子体纳米结构和波导的集成、不对称等离子体的使用、耦合等离子体-声子极化子和小扭转角双层石墨烯。最后，我们为进一步提高石墨烯 MIR PD 的性能提供了可能的方向，并讨论了这些探测器的未来应用。