Active Pixel HgCdTe Detectors With Built-in Dark Current Reduction for Near-Room Temperature Operation

High sensitivity HgCdTe infrared arrays operating at 77K can now be tailored in a wide range of wavelengths from 1 to 14 microns. However, due to the cooling requirements, they consume large amounts of power and are bulky and unsuitable for many NASA applications. During Phase I, we demonstrated the feasibility of employing dark current skimming to increase the operating temperature of HgCdTe mid-wavelength infrared devices to temperature regimes attainable by thermoelectric (TE) cooling. This work will be applied to two-color detectors and 320 ? 256 focal plane arrays during the proposed Phase II effort, leading to the next generation of HgCdTe infrared focal plane arrays. Multicolor detection will involve only an incremental development of the current skimming employed in Phase I. The resistor used in Phase I for skimming will be replaced with a photovoltaic detector that will have two functions: first, it will allow skimming by collecting part of the current flowing through the main detectors, and second, it will act as an independent detector for a second color. By employing a non-equilibrium mode of operation for the same detector, the majority and minority carrier densities will be greatly reduced. This will suppress Auger recombination processes in the active layers, and lead to dramatic increases in recombination lifetimes, dynamic impedances and detectivities. The proposed effort will exploit the excellent optoelectronic properties of bandgap tunable HgCdTe, the recent advances in the heteroepitaxial growth of this material by the flexible MBE manufacturing technique and innovative concepts such as dynamic dark current skimming and Auger suppression.