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Broadband photodetectors based on narrow bandgap 2D materials have garnered considerable interest for application in the field of optoelectronic devices. However, their large dark current hinders device performance. In this work, a PtSe2/MoS2 heterojunction was fabricated for a broadband photodetector operating within the range of visible to near-infrared. The device exhibited suppressed dark currents with a high rectification ratio of 104. The built-in electric field of the heterojunction promoted carrier separation effectively, and the device achieved excellent photoelectric performance with responsivities of 1.7 × 103, 27.52, and 21 mA/W at 635, 785, and 1550 nm wavelengths, respectively. Moreover, the specific detectivities (D*) were 2.2 × 1013 Jones (635 nm), 3.55 × 1011 Jones (785 nm), and 2.72 × 108 Jones (1550 nm). The device demonstrated a rise/fall time of 131/241 µs under 1550 nm laser illumination. Visible and near-infrared imaging detection was also demonstrated based on the heterojunction device at room temperature. This work sheds light on the remarkable potential of PtSe2/MoS2 heterojunctions in the domain of high-performance broadband photodetectors. [ABSTRACT FROM AUTHOR]

Phonon polaritons (PhPs) provide new prospects for the development of next generation nanophotonic devices due to the high optical confinement, low optical losses, and long lifetime. It is crucial to modulate the PhPs in already discovered materials in order to utilize PhPs efficiently and increase the device operability. In this work, oriented particle trace structures in α‐MoO3 are generated where the dielectric functions are broken by proton irradiation. Those particle trace structures act as in‐plane boundaries, launching and reflecting PhPs. In‐plane needle‐like PhPs in the intermediate state are obtained and finally the switching‐off of PhPs via increasing the irradiation fluences is achieved. Furthermore, the switching‐off PhPs are partly restored to original state by annealing. The method provides an opportunity to manipulate light at the nanoscale and construct in‐plane PhPs reflectors with the potential to be used for polaritonic devices and circuits. [ABSTRACT FROM AUTHOR]

In this research, we introduce a PdSe 2 /2H-MoTe 2 heterojunction photodetector that exhibits both broadband self-powered photodetection and linear/circular polarization detection capabilities. It has a broad spectral response range (covering 375-2200 nm) and reaches a peak sensitivity at 532 nm, exhibiting a notable responsivity of 7.3 × 10 3 A/W and a substantial specific detectivity of 8.5 × 10 12 Jones. Even in the near-infrared region of 1310 nm, it still has a high responsivity of 20 A/W. The self-powered photodetection capabilities of the PdSe 2 /2H-MoTe 2 heterojunction are equally impressive, covering a broad range from 375 to 1550 nm, with a responsivity of 243 mA/W, a specific detectivity of 6.46 × 10 10 Jones, a fill factor of 0.8, and an external quantum efficiency of 56.73%. Finally, simultaneous implementation of linear/circular polarization detection on the PdSe 2 /2H-MoTe 2 heterojunction provides a powerful solution for near-infrared full-Stokes polarization detectors with high integration, miniaturization, and portability.

With the advantages of a moderate band gap, high carrier mobility and good environmental stability, two-dimensional (2D) semiconductors show promising applications in next-generation electronics. However, the accustomed metal-2D semiconductor contact may lead to a strong Fermi level pinning (FLP) effect, which severely limits the practical performance of 2D electronics. Herein, the interfacial properties of the contacts between a promising 2D semiconductor, PtSe 2 , and a sequence of metal electrodes are systematically investigated. The strong interfacial interactions formed in all metal-PtSe 2 contacts lead to chemical bonds and a significant interfacial dipole, resulting in a vertical Schottky barrier for Ag, Au, Pd and Pt-based systems and a lateral Schottky barrier for Al, Cu, Sc and Ti-based systems, with a strong FLP effect. Remarkably, the tunneling probability for most metal-PtSe 2 is significantly high and the tunneling-specific resistivity is two orders of magnitude lower than that of the state-of-the-art contacts, demonstrating the high efficiency for electron injection from metals to PtSe 2 . Moreover, the introduction of h -BN as a buffer layer leads to a weakened FLP effect ( S = 0.50) and the transformation into p-type Schottky contact for Pt-PtSe 2 contacts. These results reveal the underlying mechanism of the interfacial properties of metal-PtSe 2 contacts, which is useful for designing advanced 2D semiconductor-based electronics.