Development of radiation tolerant silicon sensors

Within the CERN RD50 Collaboration, a massive R&D; programme is underway across experimental boundaries to develop silicon sensors with sufficient radiation tolerance. One research topic is to gain a deeper understanding of the connection between the macroscopic sensor properties such as radiation-induced increase of leakage current, doping concentration and trapping, and the microscopic properties at the defect level. RD50 also studies sensors made from p-type silicon bulk, which have a superior radiation hardness as they collect electrons instead of holes, exploiting the lower trapping probability of the electrons due to their higher mobility. Simulations have become important to predict the performance of silicon sensors at high fluences. They can be a useful tool to explore the large parameter space of strip sensor geometries and help to explain the charge multiplication effect occuring in sensors at high radiation levels. Charge multiplication plays an important role in sensors irradiated to high fluences and is investigated in RD50. Several studies are ongoing to exploit the effect for future silicon sensors. The latest results of the microscopic studies, the simulation activities, the performance of heavily irradiated strip sensors and the investigations on charge multiplication are presented.