Two dimensional materials based photodetectors

Two-dimensional (2D) materials represented by graphene show numerous attractive electronic, optical, mechanical, and thermal properties. Especially, the extraordinary electronic and optical properties make 2D materials promising candidates for photodetectors to replace traditional ones that fails to meet the growing demands of many fields such as high frequency communication, national security, novel biomedical imaging and so on. However, several challenges must be overcome before the realization of commercially viable 2D materials-based photodetectors, such as the low photoresponsivity of intrinsic graphene due to its low optical absorption coefficient and zero bandgap induced high recombination ratio of photo-excited carrier, the poor carrier mobility of transition-metal-dichalcogenides (TMDCs), the instability and the difficulties in preparation of black phosphorus (BP) film. In the past few years, numerous efforts have been made persistently to improve the performance of the devices and several strategies were demonstrated to be effective. Here, we reviewed the latest advances of photodetectors which are based on typical 2D materials including graphene, TMDCs, BP, hexagonal boron-nitride (h-BN) as well as new layered-material (GaS, GaSe, InSe). We discuss the experimental challenges and describe the advances of different approaches by dividing them into four categories regarding the detection wavelength ranges including ultraviolet (UV), visible to near-infrared (Vis-NIR), mid- to far- infrared (MIR-FIR), and terahertz (THz).