Scalable fabrication of mid-wavelength and long-wavelength infrared photodetectors based on narrow bandgap semiconductors: challenges and opportunities

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) detectors, which operate within the 3–14 μm wavelength range, have been extensively employed in various fields, including military, space exploration, environmental monitoring, biomedicine, and chemical analysis. While thermal detectors are commonly used, their limitations in sensitivity and response time render them less suitable for next-generation MWIR and LWIR applications. These advanced applications necessitate the use of narrow bandgap semiconductor-based photodetectors, which offer tunable optoelectronic properties and higher specific detectivity compared to thermal detectors. In this review, we provide a detailed analysis of the operational principles and manufacturing strategies of infrared photodetectors based on narrow bandgap semiconductors, which enable high-performance detection in the MWIR and LWIR regions. Our focus is specifically on scalable fabrication of MWIR and LWIR photodetectors, emphasizing devices with active areas ranging from millimeters to centimeters. Researches on large-scale fabrication of infrared photodetectors using quantum dots, two-dimensional (2D) van der Waals (vdW) materials, and three-dimensional (3D) bulk semiconductors are investigated. Finally, we summarize the remaining challenges in developing scalable narrow bandgap semiconductor-based MWIR and LWIR photodetectors for commercialization. By addressing the obstacles such as the difficulty in large-scale unform film synthesis, the requirement for cryogenic device operation, and the introduction of high-density of defect states during the hybridization processes, MWIR and LWIR photodetectors based on narrow bandgap semiconductors will pave the way for designing new sensory systems and applications in a wavelength regime that has been less developed compared to the visible and near-infrared (NIR) ranges.