Large area UV SiPMs with extremely low cross-talk

For about ten years the collaboration MEPhI-Max Plank Institute for Physics in Munich has been developing SiPMs for the MAGIC and EUSO astro-particle physics experiments. The aim was to develop UV sensitive sensors of very high photon detection efficiency, substantially exceeding that of the classical photo multiplier tubes. For very high photo detection efficiency one needs to operate SiPM under the highest Geiger efficiency, i.e., to apply a high over-voltage. This means operating SiPM under high gain that in its turn produces a very high cross-talk. For suppressing the latter adverse effect we used isolating trenches and a second p-n junction, but also special implantation profiles and layers. We produced UV sensitive SiPMs of sizes 1 mm×1 mm and 3 mm×3 mm showing a peak Photon Detection Efficiency in the range of 50-60% at a cross-talk level of only 3-5%. One of the outstanding features of the new SiPM is their extremely low sensitivity of gain to temperature variations, amounting to 0.5%/°C. Below we report on new SiPMs.