Engineering Surface Plasmons in Metal/Nonmetal Structures for Highly Desirable Plasmonic Photodetectors

Recently, small-size photodetectors have attracted considerable attention, because of their promising potential for superintegrated circuits in the photoelectric sensor system. However, the small size may disable the photodetectors or result in low photoelectric conversion efficiency, because of the optical diffraction limit and the inefficient light absorption. Encouragingly, plasmonic nanostructures take excellent advantage of light-confinement effect and electric fields enhancement at the nanoscale, providing huge opportunities to achieve small-size photodetectors while maintaining high device performance (broad photodetection range, high photoresponsivity, and fast response speed). This Review highlights the state-of-the art progress in the development of photodetectors based on various plasmonic structures. Since surface plasmons are well-controlled by the shape, size, and component of nanostructures, special emphasis will be put on the rational regulation of plasmonic nanostructures including metal nanostructures, doped semiconductors, and graphene to achieve high-performance photodetectors. In addition, the underlying enhanced mechanism is also discussed. Finally, we highlight the challenges that require deeper insights into the underlying plasmon enhanced mechanism, develop inexpensive plasmonic nanostructures for practical application, and need more research on plasmonic photodetectors based on nonmetal nanostructures and provide perspectives for future research. This Review may provide guidance for rational design of plasmonic nanostructures for small-size photodetectors with high performance.