RD50: Radiation-hard silicon for HL-LHC trackers

To harvest the maximum physics potential of the LHC , it is foreseen to significantly increase the luminosity by upgrading towards the HL-LHC (High Luminosity LHC). This will mean unprecedented radiation levels, exceeding the LHC fluences tenfold. Due to radiation damage to the silicon sensors presently used, the physics experiments will require new tracking detectors. Within the CERN RD50 Collaboration, a massive R&D; programme is underway across experimental boundaries to develop HL-LHC silicon sensors. One research topic is the connection between the macroscopic sensor properties such as radiation-induced increase of leakage current, doping concentration and trapping, and the microscopic properties. We also study 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 and allows for operation in partial depletion. A selection of the latest results achieved within the collaboration on silicon detectors irradiated at levels corresponding to HL-LHC fluences is reported in this paper.