DETECTORS FOR THE MEASUREMENT OF INTENSE ULTRAVIOLET-C RADIATION

''Solar blind'' photoelectric sensors made of metal-coated insulators have been developed for measuring intense ultraviolet-C radiation. In these detectors, ultraviolet radiation induces the photoemission of el ectrons from a semitransparent metal photocathode into an insulator. I n contrast to Schottky photodiodes, the metal coating has to generate an accumulation layer in the insulator at the interface. Pure syntheti c sapphire (Al2O3) and crystalline magnesium oxide (MgO) have been use d as insulating materials because they have proved to be thermally and photochemically stable over wide ranges of temperature and UV-C irrad iance. For potential differences of a few hundred volts across the ins ulator, photocurrents of order 1 mu A to 10 mu A have been measured at wavelengths below 250 nm and 340 nm, respectively.