ABSTRACT
Ultrafast photodetectors have many potential applications, ranging from environment monitoring to telecommunications, sensing, and basic research. Because of the inherently low absorption of normal incident light by graphene, early studies on graphene-based photodetection focused on the enhancement of light absorption. The photodetector achieved up to 20" internal quantum efficiency in the visible and near-infrared regions of the spectrum. The enhanced photoelectric response can be mainly attributed to two mechanisms. Among variant approaches to improve the light absorption of graphene photodetectors, embedding graphene into an optical cavity is ideally suited for obtaining highly efficient optical absorption in graphene, benefitting from the large increase in the optical field in the middle of the resonant cavity. Graphene photodetectors composed of a graphene/waveguide configuration show great advantages especially in the high responsivity in near-infrared and mid-infrared operational range from 1.2 µmto8µm. Plasma-based graphene terahertz photodetectors with high performance at room temperature have also been realized.
