It is foreseen to significantly increase the luminosity of the Large Hadron Collider (LHC) at CERN around 2018 by upgrading the LHC towards the SLHC (Super-LHC). Due to the radiation damage to the silicon detectors used, the physics experiments will require new tracking detectors for SLHC operation. All-silicon central trackers are being studied in ATLAS, CMS and LHCb, with extremely radiation hard silicon sensors for the innermost layers. The radiation hardness of these new sensors must surpass the one of LHC detectors by roughly one order of magnitude. Within the CERN RD50 collaboration, a massive R&D program is underway to develop silicon sensors with sufficient radiation tolerance. We will report on recent results obtained by RD50 from tests of several detector technologies and silicon materials at radiation levels corresponding to SLHC fluences. Based on these results, we will give recommendations for the silicon detector technologies to be used at the different radii of SLHC tracking systems.