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 to14 um. However, the cooling requirements make them bulky and unsuitable to be incorporated into robust autonomous sensor systems. We propose to develop detectors with high detectivity that operates at or near room temperature in the MWIR (3 to 5 um) and LWIR (8 to 12 um) atmospheric windows. These detectors are based on the active regions with HgCdTe bulk alloy layer and a secondary HgCdTe bulk alloy layer, which serves as a sink for both the dark and background currents. Room temperature or moderately cooled operation of these detectors is achieved by suppressing the Auger and radiative recombination mechanisms. We will also incorporate in each pixel a dynamic skimming that will reduce the effect of dark and background currents while enhancing the dynamic range. Therefore, we are designing detectors that are read out integrated circuit (ROIC) friendly. We plan to achieve these objectives by combining the advantages of the molecular beam epitaxy (MBE) crystal growth technique, an innovative nonequilibrium device architecture, photon recycling concepts, dynamic dark current skimming, and optimized read out circuit that will increase the operating temperature. High quality HgCdTe layers (for infrared detection) will be grown on large area (3-5") silicon substrates. This will make it possible to produce rugged, low-cost, large area focal plane arrays with higher operating temperatures and near-BLIP performance