Edge-TCT measurements with the laser beam directed parallel to the strips

Mandić, I.; Cindro, V.; Gorišek, A.; Kramberger, G.; Mikuž, M.; Zavrtanik, M.

doi:10.1088/1748-0221/10/08/p08004

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…The collected charge at a given bias voltage is calculated by integrating the current signal over time. On performing a voltage sweep at a given position on the sensor optically exposed to the laser beam, the saturation of the collected charge beyond a certain bias can be interpreted as the onset of full depletion of the sensor (Eremin et al, 1996;Fretwurst et al, 1997;Mandić et al, 2015Mandić et al, , 2013Mandić et al, , 2014.…”

Section: Diodes and Pixel Detectorsmentioning

confidence: 99%

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

et al. 2022

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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 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.

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Section: Diodes and Pixel Detectorsmentioning

confidence: 99%

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

et al. 2022

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“…Pad detectors are not ideal for Edge-TCT measurements because laser beam is running under 3 mm of readout electrode in the direction of the laser beam. As the laser light propagates through the silicon the beam spot diameter increases beyond the beam waist due to diffraction [17] and the depth of charge creation is not defined as well as in strip detectors. This effect worsens the resolution of measurement although it is expected to be somewhat less pronounced after high irradiation because of the increased laser light absorption [18].…”

Section: Edge-tctmentioning

confidence: 99%

Measurements with silicon detectors at extreme neutron fluences¹

Mandić

Cindro²,

Gorišek³

et al. 2020

J. Inst.

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Thin pad detectors made from 75 μm thick epitaxial silicon on low resistivity substrate were irradiated with reactor neutrons to fluences from 2.5× 1016 n/cm2 to 1× 1017 n/cm2. Edge-TCT measurements showed that the active detector thickness is limited to the epitaxial layer and does not extend into the low resistivity substrate even after the highest fluence. Detector current was measured under reverse and forward bias. The forward current was higher than the reverse at the same voltage but the difference gets smaller with increasing fluence. Rapid increase of current (breakdown) above ∼ 700 V under reverse bias was observed. An annealing study at 60̂C was made to 1200 minutes of accumulated annealing time. It showed that the reverse current anneals with similar time constants as measured at lower fluences. A small increase of forward current due to annealing was seen. Collected charge was measured with electrons from 90Sr source in forward and reverse bias configurations. Under reverse bias the collected charge increased linearly with bias voltage up to 6000 electrons at 2.5× 1016 n/cm2 and 3000 electrons at 1× 1017 n/cm2. Rapid increase of noise was measured above ∼ 700 V reverse bias due to breakdown resulting in worse S/N ratio. At low bias voltages slightly more charge is measured under forward bias compared to reverse. However better S/N is achieved under reverse bias. Effective trapping times were estimated from charge collection measurements under forward bias showing that at high fluences they are much longer than values extrapolated from low fluence measurements—at 1× 1017 n/cm2 a factor of 6 larger value was measured.

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Section: Edge-tctmentioning

confidence: 99%

Measurements with silicon detectors at extreme neutron fluences

Mandić,

Cindro,

Gorišek

et al. 2020

Preprint

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Thin pad detectors made from 75 µm thick epitaxial silicon on low resistivity substrate were irradiated with reactor neutrons to fluences from 2.5×10 16 n/cm 2 to 1×10 17 n/cm 2 . Edge-TCT measurements showed that the active detector thickness is limited to the epitaxial layer and does not extend into the low resistivity substrate even after the highest fluence. Detector current was measured under reverse and forward bias. The forward current was higher than the reverse at the same voltage but the difference gets smaller with increasing fluence. Rapid increase of current (breakdown) above 700 V under reverse bias was observed. An annealing study at 60 • C was made to 1200 minutes of accumulated annealing time. It showed that the reverse current anneals with similar time constants as measured at lower fluences. A small increase of forward current due to annealing was seen. Collected charge was measured with electrons from 90 Sr source in forward and reverse bias configurations. Under reverse bias the collected charge increased linearly with bias voltage up to 6000 electrons at 2.5×10 16 n/cm 2 and 3000 electrons at 1×10 17 n/cm 2 . Rapid increase of noise was measured above ∼ 700 V reverse bias due to breakdown resulting in worse S/N ratio. At low bias voltages slightly more charge is measured under forward bias compared to reverse. However better S/N is achieved under reverse bias. Effective trapping times were estimated from charge collection measurements under forward bias showing that at high fluences they are much longer than values extrapolated from low fluence measurements -at 1×10 17 n/cm 2 a factor of 6 larger value was measured. K: Silicon detectors, Extreme radiation levels * Work performed in the framework of the CERN-RD50 collaboration.

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Edge-TCT measurements with the laser beam directed parallel to the strips

Cited by 9 publications

References 15 publications

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

Measurements with silicon detectors at extreme neutron fluences¹

Measurements with silicon detectors at extreme neutron fluences

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Edge-TCT measurements with the laser beam directed parallel to the strips

Cited by 9 publications

References 15 publications

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

Measurements with silicon detectors at extreme neutron fluences1

Measurements with silicon detectors at extreme neutron fluences

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Measurements with silicon detectors at extreme neutron fluences¹