Ultraviolet (UV) Sensitive Phosphors For Silicon Imaging Detectors

The fluorescence properties of coronene, liumogen and of acrylic films doped with organic laser dyes, and their application to silicon photodetectors are discussed. Photon conversion efficiencies have been measured in the VUV and UV range and from room temperature to 108 K. The fluorescence quantum efficiency of coronene was found to be ~60%, that of liumogen ~50% and for doped acrylic as high as ~95%. All three phosphors emit between 450 and 600nm, with emission peaks at 500nm for coronene, at 510nm for doped acrylic and at 520nm for liumogen. Their fluorescence efficiencies do not change with temperature and are essentially constant over wide wave-length ranges. On coated silicon photodiodes external quantum efficiencies of up to 20% have been obtained with coronene and liumogen. With acrylic films doped with organic dyes, effective quantum efficiencies are of the order of 15% for 120nm < X < 165 nm and ~40% for λ > 190 nm. Square wave response measurements on coated linear photodiode arrays indicate that the coatings do not adversely affect spatial resolution in the visible and near infrared. In the UV, however, spatial resolution is lower than at longer wavelengths.