Stability of lumogen films on CCDs

Fluorescent lumogen films are now widely used for improving the UV quantum efficiency of CCDs and other silicon photodetectors. Because of the organic nature of lumogen and its low melting and boiling points, stability of the films has been in question. We present results of stability tests in which quantum efficiency and film characteristics are evaluated with respect to exposure to illumination, elevated temperature, and reduced pressure. Our results indicate a high tolerance to UV and visible illumination, and to slightly elevated temperatures (95 degree(s)C) at normal operating pressures. However, high vacuum conditions (10^-6 torr) can produce voids in the films at even slightly elevated temperatures.