Silicon sensors for HL-LHC tracking detectors

It is foreseen to significantly increase the luminosity of the Large Hadron Collider (LHC) at CERN by upgrading it towards the HL-LHC (High Luminosity-LHC) in order to harvest the maximum physics potential of the machine. This will result in high radiation doses for the tracking detectors. Due to the radiation damage limitations of the silicon sensors presently used, the physics experiments will require new tracking detectors for HL-LHC operation. Within the CERN RD 50 Collaboration, a research and development programme is underway across LHC Experiments boundaries to develop silicon sensors with sufficient radiation tolerance. Some of the most recent RD 50 results are presented in this paper and examples of the different research fields of RD 50 are given. Amongst these are the studies of defects and electric field measurements in devices and the performance of planar and 3D detectors before and after irradiation to doses expected at the HL-LHC. They demonstrate that the 3D technology has become a reliable option for LHC-Upgrades. In addition, observations of charge multiplication effects at very high bias voltages in a number of detectors and studies to investigate it further are reported. The paper concludes with a few achievements of the RD 50 Collaboration in light of the LHC experiments.