Transition metal dichalcogenides (TMDCs) exhibit favorable properties for optical communication in the gigahertz (GHz) regime, such as large mobilities, high extinction coefficients, cheap fabrication, and silicon compatibility. While impressive improvements in their sensitivity have been realized over the past decade, the bandwidths of these devices have been mostly limited to a few megahertz. We argue that this shortcoming originates in the relatively large RC constants of TMDC-based photodetectors, which suffer from high surface defect densities, inefficient charge carrier injection at the electrode/TMDC interface, and long charging times. However, we show in a series of papers that rather simple adjustments in the device architecture afford TMDC-based photodetectors with bandwidths of several hundreds of megahertz. We rationalize the success of these adjustments in terms of the specific physical–chemical properties of TMDCs, namely their anisotropic in-plane/out-of-plane carrier behavior, large optical absorption, and chalcogenide-dependent surface chemistry. Just one surprisingly simple yet effective pathway to fast TMDC photodetection is the reduction of the photoresistance by using light-focusing optics, which enables bandwidths of 0.23 GHz with an energy consumption of only 27 fJ/bit.

中文翻译：

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利用过渡金属二硫化物实现千兆赫光电探测


过渡金属二硫属化物 (TMDC) 在千兆赫 (GHz) 范围内表现出良好的光通信特性，例如大迁移率、高消光系数、廉价制造和硅兼容性。尽管在过去十年中其灵敏度取得了令人印象深刻的改进，但这些设备的带宽大多限制在几兆赫兹。我们认为，这一缺点源于基于 TMDC 的光电探测器相对较大的 RC 常数，其存在表面缺陷密度高、电极/TMDC 界面处的载流子注入效率低以及充电时间长的问题。然而，我们在一系列论文中表明，对设备架构进行相当简单的调整即可使基于 TMDC 的光电探测器具有数百兆赫的带宽。我们根据 TMDC 的特定物理化学性质合理化这些调整的成功，即它们的各向异性面内/面外载流子行为、大的光学吸收和硫属化物依赖性表面化学。实现快速 TMDC 光电检测的一种令人惊讶的简单而有效的途径是通过使用光聚焦光学器件来减少光阻，从而实现 0.23 GHz 的带宽，而能耗仅为 27 fJ/bit。