Gate-tunable Bi₂In₄Se₉/WSe₂ van der Waals heterostructure photodetectors for broadband photodetection

Developing photodetectors with ultra-broadband spectral coverage and dynamically tunable responsivity is critical for next-generation artificial vision systems. Here, we report a gate-tunable, ultra-broadband photodetector based on a two-dimensional (2D) Bi₂In₄Se₉/WSe₂ van der Waals heterostructure. The 2D Bi₂In₄Se₉ nanosheets were synthesized via chemical vapor transport. By exploiting the Type-II band alignment at the heterointerface, the device achieves exceptional optoelectronic performance spanning from the ultraviolet-C (UVC, 275 nm) to the near-infrared (NIR, 1064 nm) regime. Under 638 nm illumination, the heterostructure demonstrates a peak responsivity of 0.712 A W^-1, a specific detectivity of 1.16 × 10⁹ Jones, a low dark current of 1.18 pA, and a fast response time of 14.2 ms. Crucially, by modulating the Fermi level via an external gate voltage, the device exhibits highly tunable optoelectronic characteristics, achieving up to a 10-fold enhancement in responsivity. We further demonstrate the practical utility of this photodetector in high-fidelity imaging and deep-learning-based image recognition tasks. These results establish the Bi₂In₄Se₉/WSe₂ heterostructure as a highly promising platform for advanced, multifunctional optoelectronic and machine vision applications.