Ultrasensitive WSe₂/α‐In₂Se₃ NIR Photodetector Based on Ferroelectric Gating Effect

Abstract The suppression of dark current is crucial for enhancing the sensitivity of photodetectors, particularly for infrared photodetection. In this study, to overcome the low sensitivity of photodetectors in the infrared wavelength range, a photodetector comprising a 2D semiconductor (WSe₂) heterojunction and 2D ferroelectric semiconductor (α‐In₂Se₃) is developed. WSe₂ is fully depleted owing to the ferroelectric gating effect of α‐In₂Se₃; this enhanced the photodetector detectivity. In addition, photoresponsivity is increased because the n‐type α‐In₂Se₃ formed a PN junction with the p‐type WSe₂. Owing to the ferroelectric gating effect of α‐In₂Se₃, the dark current in the photodetector is suppressed above 10³ times, the photoresponsivity is increased 13.8 times from 0.16 to 2.21 A W⁻¹, and the specific detectivity is increased 437 times from 2.18 × 10⁸ Jones to 9.52 × 10¹⁰ Jones at a near‐infrared (NIR) wavelength of 980 nm. The proposed WSe₂/α‐In₂Se₃ heterostructure with an ultrasensitive characteristic in the NIR wavelength range, can contribute significantly to practical photodetector applications.