NSF Award
8907320
Charge coupled devices (CCDs) with high sensitivity throughout the vacuum ultraviolet, ultraviolet (UV), visible, and near infrared wavelengths are necessary for many proposed investigations in astronomy. The best technical approach to improve CCD sensitivity in these wavelengths is backside illumination, but such devices with high sensitivity are not available, commercially or otherwise. Commercial backside illuminated CCDs produced currently and in the past have exhibited many problems including low sensitivity, spatial and temporal variations in sensitivity, and optical distortion and interference. Recently, the need for UV sensitive CCDs for space flight applications has prompted research into methods to improve backside illuminated CCD technology. The backside charging treatments developed through this research has proved promising, but several problems still exist before sensors with the desired characteristics are produced. The Phase I research explored the problems and tradeoffs of CCD thinning and backside charging. The results obtained were promising and insightful, however two significant areas need to be further investigated. These are the problem of quantum efficiency hysteresis and the use of antireflection coatings to reduce reflection losses. Under this Phase II SBIR Award, quantum efficiency hysteresis will be reduced by chemically modifying the backside surface oxide. Antireflection coatings will be applied to the backside surface to reduce reflection loss, interference fringing, and protect the backside surface from contamination.
