2D InSe is one of the semimetal chalcogenides that has been recently given attention thanks to its excellent electrical properties, such as high mobility near 1000 cm 2 V −1 s −1 and moderate band gap of ≈1.26 eV suitable for IR detection. Here, high-performance visible to near-infrared (470-980 nm wavelength (λ)) photodetectors using surface-doped InSe as a channel and few-layer graphenes (FLG) as electrodes are reported, where the InSe top region is relatively p-doped using AuCl 3. The surface-doped InSe photodetectors show outstanding performance, achieving a photoresponsivity (R) of ≈19 300 A W −1 and a detectivity (D*) of ≈3 × 10 13 Jones at λ = 470 nm, and R of ≈7870 A W −1 and D* of ≈1.5 × 10 13 Jones at λ = 980 nm, superior to previously reported 2D materialbased IR photodetectors operating without an applied gate bias. Surface doping using AuCl 3 renders a band bending at the junction between the InSe surface and the top FLG contact, which facilitates electron-hole pair separation and immediate photodetection. Multiple doped or undoped InSe photodetectors with different device structures are investigated, providing insight into the photodetection mechanism and optimizing performance. Encapsulation with hexagonal boron nitride dielectric also allows for 3-month stability.

We investigate transport properties and scattering mechanisms of high-mobility InSe nanosheets, encapsulated by hBN, via four-terminal measurements. The measured conductivities increase as temperature (T) decreases, showing a metallic behavior at gate voltages above a threshold voltage, in contrast to the metal–insulator transition occurring at a high gate voltage observed in the two-terminal conductance of InSe. Phonon-limited and impurity-limited mobilities were separated for each carrier density (n) and T. Extracted impurity-limited mobility values are weakly dependent on n due to dominant short-range scatterers, while phonon-limited mobility values decrease as n increases due to second subband occupation and increased electron–phonon scattering.

Low- or self-powered infrared sensors can be used in a broad range of applications, including networking mobile edge devices and image recognition for autonomous driving technology. Here, we show state-of-the-art...