In order to harvest the maximum physics potential of the CERN Large Hadron Collider (LHC), it is foreseen to significantly increase the LHC luminosity by upgrading the LHC towards the HL-LHC (High Luminosity LHC) [1] . Especially the final upgrade (Phase-II Upgrade) foreseen beyond 2020 will mean unprecedented radiation levels. Due to the radiation damage limitations of the silicon sensors presently used, the physics experiments will require new tracking detectors for HL-LHC operation. All-silicon central trackers are being studied in ATLAS, CMS and LHCb, with extremely radiation hard silicon sensors to be used for the innermost layers. 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. A further area of activity is the development of advanced sensor types like 3D silicon detectors designed for the extreme radiation levels expected for the vertexing layers at the HL-LHC. Results from irradiation with a mix of different particle types as expected for the sLHC are also given. Recent observations of charge multiplication effects in heavily irradiated detectors at very high bias voltages point towards a new way to achieve sizeable signals after high fluences. Results for several detector technologies and silicon materials at radiation levels corresponding to HL-LHC fluences are presented in this article, demonstrating the availabilty of silicon detectors with sufficient radiation hardness for the different radii of tracking systems in the LHC detector upgrades.