Development of pixel detectors for the IBL and HL-LHC ATLAS experiment upgrade

This thesis presents the development of advanced silicon technology detectors fabricated at CNM-Barcelona for High Energy Physics (HEP) experiments. The pixel size of the tracking silicon detectors for the upgrade of the HL-LHC will have to decrease in size in order to enhance the resolution in position for the measurements and they need to have lower occupancy for the electronics. The future experiments at CERN will cope with fuences up to 2 x 10^^16 neq/cm2, and the smaller 3D silicon detectors will have less trapping of the electron-holes generated in the bulk leading to a better performance under high radiation environment. This thesis studies silicon detectors fabricated at CNM-Barcelona applied to HEP experiments with two different kinds of novel technologies: 3D and Low Gain Avalanche Detectors (LGAD). The 3D detectors make it possible to reduce the size of the depleted region inside the detector and to work at lower voltages, whereas the LGAD detectors have an intrinsic gain which increases the collected signal with a multiplication mechanism. Chapter 1 introduces the silicon detectors applied to HEP experiments. Chapters 2 and 3 explore the new designs for 3D silicon detectors fabricated at CNM-Barcelona. 3D silicon detectors were first introduced in a HEP experiment in 2013 for a new ATLAS layer, the Insertable B layer (IBL), and some of them are characterized in this work. Now, it is expected that 3D silicon detectors with smaller pixel size will be operative for the next ATLAS upgrade, and they are also simulated in this thesis. Chapter 4 is devoted to segmented LGAD detectors fabricated on epitaxial wafers with the intention to decrease the thickness of the detector and increase the charge collected with the multiplication mechanism. This thesis shows technological simulations, fabrication process, electrical simulations and electrical and charge characterization of those devices.