High-performance infrared (IR) photodetectors made by low dimensional materials promise a wide range of applications in communication, security and biomedicine. Moreover, light-harvesting effects based on novel plasmonic materials and their combinations with two-dimensional (2D) materials have raised tremendous interest in recent years, as they may potentially help the device complement or surpass currently commercialized IR photodetectors. Graphene is a particularly attractive plasmonic material because graphene plasmons are electrically tunable with a high degree of electromagnetic confinement in the mid-infrared (mid-IR) to terahertz regime and the field concentration can be further enhanced by forming nanostructures. Here, we report an efficient mid-IR room-temperature photodetector enhanced by plasmonic effect in graphene nanoresonators (GNRs)/graphene heterostructure. The plasmon polaritons in GNRs are size-dependent with strong field localization. Considering that the size and density of GNRs are controllable by chemical vapor deposition method, our work opens a cost-effective and scalable pathway to fabricate efficient IR optoelectronic devices with wavelength tunability.

Black phosphorus (BP) is a promising material for ultrafast and broadband photodetection because of its narrow bandgap from 0.35 eV (bulk) to 1.8 eV (monolayer) and high carrier mobility. Although photodetectors based on BP with different configurations have been reported, high photosensitivity was mostly observed in the visible range. A highly efficient BP-based infrared photodetector operated in the telecom spectral range, especially at 1550 nm, has not been demonstrated. Here, we report a Schottky-type photodetector based on thin BP flakes, operating in a broad spectral range from visible (635 nm) to infrared (1550 nm). A responsivity as high as 230 A·W 1 was achieved at 1550 nm with a source-drain bias of 1 V. The rise time is 4.8 ms, and the fall time is 6.8 ms. Under light illumination and external bias, the Schottky barrier between the BP and metal was reduced, leading to efficient photocurrent extraction. The unprecedented performance of the BP photodetector indicates intriguing potential for sensing, imaging, and optical communication.

Atomically thin MoS₂ films have attracted significant attention due to excellent electrical and optical properties. The development of device applications demands the production of large-area thin film which is still an obstacle. In this work we developed a facile method to directly grow large-area MoS₂ thin film on SiO₂ substrate via ambient pressure chemical vapor deposition method. The characterizations by spectroscopy and electron microscopy reveal that the as-grown MoS₂ film is mainly bilayer and trilayer with high quality. Back-gate field-effect transistor based on such MoS₂ thin film shows carrier mobility up to 3.4 cm² V^?1 s^?1 and on/off ratio of 10⁵. The large-area atomically thin MoS₂ prepared in this work has the potential for wide optoelectronic and photonic device applications.