Charge Transfer in InAs@ZnSe‐MoS₂ Heterostructures for Broadband Photodetection

Abstract Absorbing near‐infrared (NIR) photons, with longer wavelengths, in atomically thin monolayer MoS 2 presents a significant challenge due to its weak optical absorption and narrow absorption bands. Consequently, MoS 2 ‐based photodetector devices often experience low responsivity and a limited detection window. Herein, a novel InAs@ZnSe core@shell/1L‐MoS 2 heterostructure, leveraging InAs@ZnSe as the primary infrared‐absorbing material and exploiting the formation of a type‐II heterostructure is showcased. Steady‐state and time‐resolved spectroscopy, along with optoelectronic characterization, are employed to investigate photo‐induced charge transfer dynamics. The results show efficient hole transfer to InAs@ZnSe upon excitation of both materials. Instead, with selective excitation of InAs@ZnSe, electron transfer is observed from InAs@ZnSe to the 1L‐MoS 2 . The heterostructure demonstrates a broadband photoresponse spanning the wavelength range of 300 to 850 nm, exhibiting a Responsivity of ≈10 3 A/W and Detectivity of ≈10 11 Jones. The signal‐to‐noise ratio substantially increases by 3 to 4 orders of magnitude for 700 and 850 nm excitation compared to pristine 1L‐MoS 2 . The enhancement in photoresponse and signal‐to‐noise ratio is attributed to increased absorption, which helps eliminate defect and trap states, thereby promoting the photogating effect.