Highly Efficient Infrared Photodetection in a Gate-Controllable Van der Waals Heterojunction with Staggered Bandgap Alignment.

In recent years, various van der Waals (vdW) materials have been used in implementing high-performance photodetectors with high photoresponsivity over a wide detection range. However, in most studies reported so far, photodetection in the infrared (IR) region has not been achieved successfully. Although several vdW materials with narrow bandgaps have been proposed for IR detection, the devices based on these materials exhibit notably low photoresponsivity under IR light illumination. Here, highly efficient near-infrared (NIR) photodetection based on the interlayer optical transition phenomenon in a vdW heterojunction structure consisting of ReS ₂ and ReSe ₂ is demonstrated. In addition, by applying the gate-control function to the two-terminal vdW heterojunction photodetector, the photoresponsivity is enhanced to 3.64 × 10 ⁵ A W ^-1 at λ = 980 nm and 1.58 × 10 ⁵ A W ^-1 at λ = 1310 nm. Compared to the values reported for previous vdW photodetectors, these results are the highest levels of photoresponsivity in the NIR range. The study offers a novel device platform for achieving high-performance IR photodetectors.