Ultrabroadband Photodetector Based on Ferromagnetic van der Waals Heterodiode

Abstract The discovery of 2D ferromagnetic (FM) van der Waals (vdW) semiconductors with narrow bandgap and p ‐type transport behavior makes them promising for infrared photodetection. Here, a 2D vdW heterodiode uncooled long‐wave infrared (LWIR) photodetector by stacking a p ‐type 2D FM material CrSiTe 3 on top of an n ‐type transition metal dichalcogenides (TMDs) MoS 2 is reported. A good rectification ratio > 10 2 and an ultra‐broadband photoresponse from 0.52 to 10.6 μ m are demonstrated. The photoresponsivity of up to 20.7 A W −1 and the external quantum efficiency (EQE) of up to 4031.7% are obtained under a 1310 nm laser at a − 1 V bias in ambient, which indicates that these CrSiTe 3 –MoS 2 p–n junction devices have a good photovoltaic response. Meanwhile, the photovoltaic responsivity up to 0.15 A W −1 , EQE up to 29.7%, and fast response with a decay time of 2.8 μ s at 637 nm are demonstrated. In addition, the room temperature mid‐wave infrared (MWIR) specific detectivity and LWIR specific detectivity of CrSiTe 3 –MoS 2 is 6.1 × 10 9 cm Hz 1/2 W −1 and 1.93 × 10 9 cm Hz 1/2 W −1 , respectively. These observations open up possibilities for developing high‐sensitive infrared detection based on the valley optical selection rule and LWIR image technology.