Diamond detectors for LYRA, the solar VUV radiometer on board PROBA2

New pin-photodiode and metal–semiconductor–metal (MSM) photoconductor devices based on diamond material have been produced showing high responsivity around 200 nm. LYRA, the Large Yield RAdiometer, will use such detectors for the first time for a solar physics space instrument. A set of measurement campaigns was carried out to obtain their XUV-to-VIS characterization (responsivity, linearity, stability and homogeneity). The diamond pin and MSM photodetectors exhibit a high responsivity of 27 mA/W around 200 nm and demonstrate a visible rejection ratio (200 nm versus 500 nm) of six and four orders of magnitude, respectively. We show that these diamond photodetectors are sensitive sensors for the wavelength range of interest (1 nm to 220 nm), stable within a few percent, with a good linearity and moderate homogeneity.