A polarization-sensitive photodetector based on a b-AsP/In₂Se₃ heterostructure

van der Waals (vdW) heterojunctions, composed of two-dimensional materials, offer competitive opportunities in the design and realization of versatile and high-performance electronic and optoelectronic devices. Polarization-sensitive infrared (IR) photoelectric detection plays an important role in optical communication, environmental monitoring, and remote sensing imaging. Here, we report a mirror electrode-enhanced black arsenic phosphorus (b-AsP) and indium selenide (In₂Se₃) b-AsP/In₂Se₃ vdW heterojunction photodetector. The device enables wide-band detection from the solar-blind ultraviolet (SBUV) to the mid-wave infrared (MWIR) spectral range. The device showed an excellent performance, including a high photoresponsivity (R) of 4129.3 A W^-1, competitive high specific detectivity (D*) of 2.8 × 10¹¹ cm Hz^1/2 W^-1, and very low noise equivalent power (NEP) of 2.8 × 10^-15 W Hz^-1/2 with 0.32 nW of 275 nm SBUV light at 1 V bias. Moreover, the device demonstrated a very fast speed with a rise time (τ_r) of 5.8 μs, a decay time (τ_d) of 2.8 μs, and a high dichroic ratio of ∼2.12 under 637 nm laser irradiation. This work provides a way to realize polarization-sensitive detectors with high sensitivity and fast speed.