Highly Sensitive Long‐Wave Infrared Photodetector Based on Two‐Dimensional Hematite α‐Fe₂O₃

Abstract Ambient temperature long‐wavelength infrared (LWIR) photodetection has many critical applications ranging from thermal imaging and optical communications to night vision cameras. Currently, high performance, low cost, air stability, and ultra‐broadband response still constitute challenges. Here, the study demonstrates a high‐performance uncooled LWIR photodetector using 2D hexagonal α‐Fe₂O₃ single crystal nanoflakes, which are synthesized via chemical vapor deposition. The 2D α‐Fe₂O₃ photodetector realizes high specific detectivity (D^*) of 3.28×10⁹ cmHz^1/2 W⁻¹ and very low noise equivalent power of 8.94×10⁻¹⁴ W Hz^−1/2 with 10.6 µm laser. The photo bolometer effect is responsible for the photoresponse in the infrared range with a large temperature coefficient resistance of −241.2% K⁻¹. This study shows a new type of potential broadband response material and provides a promising LWIR optoelectrical device with good air stability.