Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

Shudhashil Bharthuar, Maria Golovleva, Mihaela Bezak, Erik Brücken, Akiko Gädda, Jaakko Härkönen, Aneliya Karadzhinova, Nikita Kramarenko, Stefanie Kirschenmann, Pirkitta Koponen, Panja Luukka, Kenichiro Mizohata, Jennifer Ott, Eija Tuominen

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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 10(15) protons/cm(2) 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.

TidskriftFrontiers in materials
Antal sidor19
StatusPublicerad - 19 jan. 2022
MoE-publikationstypA1 Tidskriftsartikel-refererad


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