Ultra-broadband photodetection based on two-dimensional layered Ta₂NiSe₅ with strong anisotropy and high responsivity

Broadband photodetectors have attracted substantial attention in recent years. The ternary chalcogenide Ta₂NiSe₅ is a layered material with a direct narrow-band gap (E_g ~ 0.33 eV) which possesses greatly potential to broadband photodetectors. Here, high-quality bulk Ta₂NiSe₅ was synthesized by Chemical Vapor Transport (CVT) method. We demonstrate a photodetector based on exfoliated Ta₂NiSe₅ nanoflake, which exhibits a broadband photo-response from 405 nm to 4300 nm. Meanwhile, its main characteristics are superior to other typical 2D materials: high responsivity ~198.1 A W⁻¹ at 1350 nm and ultrafast response time of ~27.4 µs. Long-time photocurrent reproducibility shows that the photodetector has excellent stability under atmosphere. Furthermore, the scanning photocurrent mapping reveals the photoconductive mechanism of Ta₂NiSe₅ photodetector. In addition, the anisotropic ratio of the photocurrent is ~1.46. The broadband photodetection, high responsivity, anisotropic and environmental stability achieved simultaneously in Ta₂NiSe₅ photodetector, which are promising for neotype electronics and optoelectronics field.