Self-Assembly High-Performance UV-vis-NIR Broadband β-InSe/Si Photodetector Array for Weak Signal Detection.

The emergence of a rich variety of layered materials has attracted considerable attention in recent years because of their exciting properties. However, the applications of layered materials in optoelectronic devices are hampered by the low light absorption of monolayers/few layers, the lack of p-n junction, and the challenges for large-scale production. Here, we report a scalable production of β-InSe/Si heterojunction arrays using pulsed-laser deposition. Photodetectors based on the as-produced heterojunction array are sensitive to a broadband wavelength from ultraviolet (370 nm) to near-infrared (808 nm), showing a high responsivity (5.9 A/W), a decent current on/off ratio (∼600), and a superior detectivity (4.9 × 10 jones), simultaneously. These figures-of-merits are among the best values of the reported heterojunction-based photodetectors. In addition, these devices can further enable the detection of weak signals, as successfully demonstrated with weak light sources including a flashlight, lighter, and fluorescent light. Device physics modeling shows that their high performance is attributed to the strong light absorption of the relatively thick β-InSe film (20.3 nm) and the rational energy band structures of β-InSe and Si, which allows efficient separation of photoexcited electron-hole pairs. These results offer a new insight into the rational design of optoelectronic devices from the synergetic effect of layered materials as well as mature semiconductor technology.