High Operating Temperature, Broadband Visible/Infrared HgCdTe Photodetectors

ABSTRACT:We propose the development of broadband high operating temperature two-color focal plane arrays (FPAs) that will allow simultaneous detection of radiation in the visible and infrared bands from the same target points. The first band will cover the 400 nm to 4 micron wavelength range and will be based on 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 Auger suppressed architecture. This architecture allows for dark currents similar with the ones observed in the first color.During the Phase I program, we demonstrated Auger suppression for the LWIR band and diffusion limited behavior for the MWIR band. Based on the successful Phase I effort, this proposed Phase II program will transition the technology to 2D FPAs. This goal will be accomplished by optimization of the HgCdTe device geometry and architecture, grow by molecular beam epitaxyHgCdTe heterostructures suitable for broadband detection, fabricate detector arrays through a novel mosaic process, develop indium bump formation for variable height pixels and hybridize detector arrays to the read-out circuits. A packaged FPA will be delivered to Air Force.BENEFIT:Single detector and small array product line would have a range of commercial applications, such as spectrometry, thermometry, high-end industrial manufacturing, and hotspot detection. Additionally, larger arrays, due to their lower costs and light weight characteristics (TE-base), will have applications in astronomy, geophysics, geology, law enforcement, remote environmental sensing, search and rescue, and emergency response including firefighting. If multistage TE coolers are used, the product would also have applications in medical systems, commercial airlines, and ground transportation. 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 is 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 these industries, which can significantly benefit from high performance, uncooled detectors. Uncooled photodetectors designed for wide spectral detection can be useful for high sensitivity detection, particularly for low flux applications, and can replace or be used in conjunction with conventional thermal detectors.