Quest 2026

PbSe detectors remain a leading choice for the 3–5 µm spectral range due to their strong balance of size, weight, power consumption, cost, and performance, particularly under uncooled operating conditions. The most common fabrication method is Chemical Bath Deposition (CBD), where substrates are immersed in a chemical solution to deposit polycrystalline thin films. CBD is attractive because of its simplicity, scalability, and compatibility with large-area manufacturing; however, challenges remain in process reproducibility and film uniformity. 

A key step in device fabrication is sensitization, which activates the film’s photoresponse. As-grown PbSe films typically exhibit low photosensitivity and therefore require thermal treatment in controlled atmospheres, commonly involving oxygen- and iodine-based processes. These treatments introduce chemical and structural modifications, including the formation of lead-oxide and lead-oxyselenide phases (e.g., PbSeO₃) at grain boundaries, which are believed to strongly influence carrier transport and photoconductive gain. Several models have been proposed to explain the operation of sensitized PbSe detectors, including grain-boundary barrier modulation, junction-like charge-separation effects at crystallite surfaces, and trap-assisted conduction. The exact operating mechanism remains an active area of research, emphasizing the need for deeper material and device-level understanding.