Fully Epitaxial Uncooled PbSe/CdSe/Bi ₂ Se ₃ Heterojunction Barrier Middle Infrared Detector

ABSTRACT Mid‐ and long‐wavelength infrared photodetectors based on conventional narrow‐bandgap materials often suffer from high dark currents at room temperature due to their inherent material properties, limiting their performance. Here, a pBn ⁺ unipolar barrier infrared photodetector with epitaxial PbSe/CdSe/Bi ₂ Se ₃ architecture was proposed, which could effectively suppress dark current and enable superior room temperature operation. By integrating a wide‐bandgap CdSe barrier layer between PbSe and Bi ₂ Se ₃ pn heterojunction, the barrier device achieves significant dark current reduction, reaching 66.1 mA/cm ² at room temperature. Additionally, the barrier detector exhibits a strong infrared photoresponse with a responsivity of 0.59 A/W and a detectivity of 2.29 × 10 ⁹ cm·Hz ^1/2 ·W ⁻¹ under 2.7 µm illumination. Based on its compact design, lightweight structure, and excellent performance at room temperature, the proposed pBn ⁺ PbSe‐based barrier photodetector holds great promise for both military and civilian infrared applications.