Radiation Damage Studies of Silicon Low Gain Avalanche Detectors

Abstract

Silicon pad, pixel and strip sensors constitute fundamental components in numerous particle physics experiments at the Large Hadron Collider (LHC) and around the globe. HighLuminosity LHC (HL-LHC) experiments will face very harsh radiation environments and superposition of multiple proton–proton collisions per bunch crossing. The technological challenges to enhance radiation hardness in combination with sensor timing precision to disentangle the multiple collisions per bunch crossing are pushed even further for the proposed Future Circular Collider (FCC-hh).Low Gain Avalanche Detectors (LGADs) have shown to be promising candidates to face the challenges of future particle detection. LAGDs are semiconductor detectors featuring signal amplification, achieved by incorporating a thin, highly-doped p + -layer within the p-type bulk material and thereby generating a high electric field region. This field leads to charge multiplication by impact ionisation of the primary electrons, creating additional electron–hole pairs and a gain of the signal. Therefore, LGADs have a remarkable timing performance and low Signal-to-Noise ratio and will be used for the Phase II timing detectors of ATLAS and CMS.However, LGADs suffer from radiation induced performance degradation manifesting as a loss of signal gain. In this doctoral thesis, the radiation-induced degradation of LGAD sensors will be characterized. Measurements will be presented, along with simulations of radiation effects and performance degradation in LGADs, with the goal of achieving a better theoretical understanding of the devices and enabling further design optimizations.