Ternary 2D Layered Material FePSe 3 and Near‐Infrared Photodetector

The preparation of ternary 2D layered material (2DLM) FePSe 3 and field‐effect transistor (FET) type photodetector are investigated. By advancing an optimized chemical vapor transport method, bulk crystal FePSe 3 is synthesized within several growth hours instead of routinely required weeks, from which 2DLM FePSe 3 flakes with a thickness of ≈22.0 nm and high crystalline quality are obtained through mechanical exfoliation. Ohmic contacts for FET structure with good linear conductivity and thermal stability are implemented through the combination of electron‐beam lithography and thermal evaporation techniques. Transfer characteristics prove the p‐type conductivity of the 2DLM FePSe 3 channel. The transistor devices exhibit good performance at 637 nm with a detectivity of 1.17 × 10 7 Jones. More importantly, a wide photocurrent spectrum from visible (450 nm) to near‐infrared (940 nm) of ternary 2DLMs is observed, which is attributed to the improvement of crystal quality of 2DLM, relatively low surface defect states, and high‐performance Ohmic electrodes. This work promotes the development of ternary 2DLM and photodetector that are still in their infancy towards continuous broad‐spectrum technology.