Radiation hardness of CMOS detector prototypes for ATLAS Phase II ITk upgradeHiti, Bojan (Avtor) Mandić, Igor (Mentor) ATLAS ITkCERNHL-LHCSilicon detectorsRadiation damageCharge transportAcceptor removalRadiation hard detectorsDMAPSHV-CMOSHR-CMOSThis thesis presents a study of charge collection properties and its dependence on displacement damage caused by irradiation in CMOS detector prototypes developed for the phase-II upgrade of the Inner Tracker (ITk) in ATLAS experiment. Investigated samples were developed in four separate development lines and manufactured in different industrial processes. The main design parameters studied in this work are initial resistivity and the size of collection electrode. Samples were irradiated with reactor neutrons to fluences between $\rm 10^{13}~n_{eq}/cm^2$ and $\rm 10^{16}~n_{eq}/cm^2$ and with protons to fluences between $\rm 10^{14}~n_{eq}/cm^2$ and $\rm 3.6~\dot~10^{15}~n_{eq}/cm^2$. Charge collection in the samples was characterised with Edge-TCT, radioactive $\rm ^{90}Sr$ beta source and in a highly energetic pion test beam. Measurements of effective space charge concentration with Edge-TCT show significant radiation dependence influenced by initial acceptor removal. Acceptor removal is slower at lower initial substrate resistivity and is typically finished at a fluence of $\rm \sim 10^{13}~n_{eq}/cm^2$ in highly resistive $\rm 2~k\Omega cm$ material and $\rm \sim 10^{15}~n_{eq}/cm^2$ in material with initial resistivity of $\rm 20~\Omega cm$. Acceptor removal may cause the increase of the depth of depletion zone in certain range of fluences which was observed by both Edge-TCT and $\rm ^{90}Sr$. Measurements of in-pixel hit detection efficiency with test beam revealed significant efficiency gaps on pixel edges in samples with a small collection electrode after irradiation. These results prompted modifications of pixel design in form of additional implanted structures which are expected to significantly improve detector performance.20202020-04-23 08:15:02Doktorsko delo/naloga115344VisID: 106425COBISS_ID: 3418724sl