Title: Radiation hardness characterisation of CMOS sensors for the ATLAS ITK Pixel at HL-LHC and future Trackers
Other Titles: null
Language: English
Authors: Dachs, Florian 
Qualification level: Doctoral
Keywords: Particle Detectors; Silicon Detectors; Radiation Effects
Advisor: Krammer, Manfred 
Issue Date: 2020
Number of Pages: 143
Qualification level: Doctoral
Abstract: 
Diese Arbeit beschäftigt sich mit der Entwicklung eines neuartigen monolithischen Silizium-Pixeldetektors names `MALTA' in Kooperation mit dem Halbleiterhersteller TowerJazz. Ergebnisse aus Strahltests zeigen, dass erste Prototypen nach Bestrahlung eine unzureichende Detektionseffizienz am Pixelrand aufweisen. Dies wird durch eine starke Verringerung der Ladungssammlungseffizienz aufgrund eines unerwartet schwachen lateralen elektrischen Feldes erklärt. Die Wirksamkeit der anschließenden Änderungen an den Doping-Profilen und der CMOS Schaltung im MALTA-Pixel wird ebenfalls durch Strahltests bestätigt und es kann gezeigt werden, dass neue Versionen von MALTA die durch den ITk gestellten Anforderungen an die Detektionseffizienz nach Bestrahlung erfüllen können.

Due to the installation of the `High Luminosity' upgrade at the LHC, ATLAS will be extensively upgraded as well in 2025. This includes an area of 12m2 which must be covered by silicon pixels and motivates the development of monolithic active pixel sensors manufactured via industrial CMOS processes to reduce production cost and increase production throughput. Further, monolithic detectors can be built with less material budget compared to state-of-the-art hybrid detectors which reduces the scattering of collision products by the detector.This work focuses on the development of a novel monolithic silicon pixel detector called `MALTA' in cooperation with the TowerJazz foundry. Results from beam tests show that first prototypes have a much reduced detection efficiency at pixel borders after irradiation. This is explained by a significantly reduced charge collection efficiency at pixel borders due to an unexpectedly weak lateral electric field. The effectiveness of the following modifications to the doping profiles and CMOS circuitry in the MALTA pixel is confirmed in further beam tests and it can be shown that later MALTA prototypes fulfill the detection efficiency requirements of the ITk after irradiation.
URI: https://doi.org/10.34726/hss.2020.28966
http://hdl.handle.net/20.500.12708/16521
DOI: 10.34726/hss.2020.28966
Library ID: AC16112326
Organisation: E141 - Atominstitut 
Publication Type: Thesis
Hochschulschrift
Appears in Collections:Thesis

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