Hot Wall Epitaxy of Mixed Lead Chalcogenides in Resonant Cavity Structures

The US Navys Combined Electro-Optical/Infrared Surveillance and Response System (CESARS) is seeking medium wavelength infrared detectors (MWIR) that can use spectral signatures in 2-5 m range to remotely detect and characterize explosive chemicals or chemical warfare species. Group III-V and II-VI compound semiconductors-based focal plane arrays (FPAs) have the desired properties in the MWIR for remote detection of chemical species, however they require cryogenic cooling to minimize dark current noise, which adds significantly to the size, weight, power and cost of the detector. On the other hand, narrow bandgap lead salts can operate at >200 K, and are also more chemically stable. Binary lead salts have been well-studied for MWIR applications. However, mixed chalcogenides that offer wavelength tunability, are not commercially available mainly due to challenges in manufacturing device-grade material. We propose to develop a high-quality ternary lead salt detector which can operate at room temperature with high detectivity, and with cutoff wavelength spanning the range of 3.5 to 4.6 m. A novel cost-effective method for fabricating high-quality films will be demonstrated. Such films will then by integrated into Resonant Cavity-Enhanced FPA architecture to improve detectivity, QE and tunability of the MWIR detectors.