High-performance visible-UV CCD imagers for space-based applications

focusing on work on large device formats, improvements in quantum efficiency, and reduction of CCD degradation in the natural space-radiation environment. Research was based on a 420 x 420-pixel frame-transfer device and a new 1024 x 1024-pixel device. To obtain high quantum efficiency from the visible into the UV, a technology for making back-illuminated versions of these devices is being developed. Quantum efficiencies greater than 80 percent in the 500-800 nm band have been obtained with a SiO antireflection coating. Particular attention is given to the problem of charge-transfer inefficiency degradation caused by energetic protons in space-based systems. It is shown that CCDs can be significantly hardened to radiation effects by a combination of special buried channel potential profiles and operation at temperatures around 150 K, where the trap sites created by the protons have emission times much longer than the clock periods.