Broadband High Operating Temperature Focal Plane Array (FPA)

ABSTRACT: We propose the development of broadband, two-color focal plane arrays (FPAs) that will allow the detection of radiation in the visible and infrared (IR) bands from the same target points with registration within the optical limit. The first band will cover the 400 nm to 4 micron wavelength range and will be based on EPIR"s double-layer planar heterostructures technology. The backside-illuminated array will have the substrate removed to allow for visible detection. The second color will cover the 4-11 micron wavelength range and will be based on an Auger-suppressed architecture. This architecture will allow for dark currents similar to the ones observed in the first color (400 nm 4 micron). The development of a broadband visible/IR FPA poses several challenges in the areas of detector design, material, device physics, fabrication process, integration and testing. The purpose of our proposed research is to address these challenges and demonstrate a high-performance camera system that incorporates an HgCdTe-based detector array. Phase I research will first focus on computational studies related to the proposed detector structure optimization. The results of the initial simulations will be used to guide the material growth process, and devices will subsequently be fabricated, characterized and delivered to the Air Force. BENEFIT: There are a wide number of applications for compact, low power detectors in areas such as spectrometry, thermometry, industrial manufacturing, and hotspot detection. Portable, handheld thermal imaging systems used for diagnostic detection are ideal candidates for lightweight, low power detectors. Moreover, large uncooled and thermoelectrically-cooled IR arrays have various uses in defense, astronomy, geology, law enforcement, remote environmental sensing, and emergency response. Improved high-performance HgCdTe detectors without cryo-cooling requirements are of great interest to the industry since many customers who may not have access to liquid nitrogen could benefit from having improved detection capability. The lightweight, low power design of the proposed detector would create a new market for the industry, which would significantly benefit from performance, uncooled detectors. Uncooled photodetectors designed for wide spectral detection can be used for high-sensitivity detection, particularly for low flux applications, and can replace, or be used in conjunction with conventional thermal detectors.