Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2022-01-19
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Mcode
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Language
en
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Frontiers in materials, Volume 8
Abstract
An increase in the radiation levels during the high-luminosity operation of the Large Hadron Collider calls for the development of silicon-based pixel detectors that are used for particle tracking and vertex reconstruction. Unlike the conventionally used conductively coupled (DC-coupled) detectors that are prone to an increment in leakage currents due to radiation, capacitively coupled (AC-coupled) detectors are anticipated to be in operation in future collider experiments suitable for tracking purposes. The implementation of AC-coupling to micro-scale pixel sensor areas enables one to provide an enhanced isolation of radiation-induced leakage currents. The motivation of this study is the development of new generation capacitively coupled (AC-coupled) pixel sensors with coupling insulators having good dielectric strength and radiation hardness simultaneously. The AC-coupling insulator thin films were aluminum oxide (Al2O3) and hafnium oxide (HfO2) grown by the atomic layer deposition (ALD) method. A comparison study was performed based on the dielectric material used in MOS, MOSFET, and AC-coupled pixel prototypes processed on high resistivity p-type Magnetic Czochralski silicon (MCz-Si) substrates. Post-irradiation studies with 10 MeV protons up to a fluence of 1015 protons/cm2 suggest HfO2 to be a better candidate as it provides higher sensitivity with negative charge accumulation on irradiation. Furthermore, even though the nature of the dielectric does not affect the electric field within the AC-coupled pixel sensor, samples with HfO2 are comparatively less susceptible to undergo an early breakdown due to irradiation. Edge-transient current technique (e-TCT) measurements show a prominent double-junction effect as expected in heavily irradiated p-type detectors, in accordance with the simulation studies.Description
Funding Information: The research is supported by the Magnus Ehrnrooth Foundation (research grant number 200 011). This study was partially funded by the Academy of Finland (project number 314 473), ?Multi-spectral photon-counting for medical imaging and beam characterization.? Publisher Copyright: Copyright © 2022 Bharthuar, Golovleva, Bezak, Brücken, Gädda, Härkönen, Karadzhinova-Ferrer, Kramarenko, Kirschenmann, Koponen, Luukka, Mizohata, Ott and Tuominen.
Keywords
AC-pixel sensors, ALD (atomic layer deposition), alumina, hafnia, magnetic Czochralski, MOS capacitor, MOSFET, radiation hardness
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Bharthuar , S , Golovleva , M , Bezak , M , Brücken , E , Gädda , A , Härkönen , J , Karadzhinova-Ferrer , A , Kramarenko , N , Kirschenmann , S , Koponen , P , Luukka , P , Mizohata , K , Ott , J & Tuominen , E 2022 , ' Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications ' , Frontiers in materials , vol. 8 , 769947 . https://doi.org/10.3389/fmats.2021.769947
