This paper reports the latest technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are ...based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n++–p+–p structure, where the doping profile of the p+ layer is optimized to achieve high field and high impact ionization at the junction.
The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.
Silicon detectors with intrinsic charge amplification implementing a n++-p+-p structure are considered as a sensor technology for future tracking and timing applications in high energy physics ...experiments. The performance of the intrinsic gain in Low Gain Avalanche Detectors (LGAD) after irradiation is crucial for the characterization of radiation hardness and timing properties in this technology. LGAD devices irradiated with reactor neutrons or 800 MeV protons reaching fluences of 2.3×1016neq/cm2 were characterized using Transient Current Technique (TCT) measurements with red and infra-red laser pulses. Leakage current variations observed in different production lots and within wafers were investigated using Thermally Stimulated Current (TSC). Results showed that the intrinsic charge amplification is reduced with increasing fluence up to 1015neq/cm2 which is related to an effective acceptor removal. Further relevant issues were charge collection homogeneity across the detector surface and leakage current performance before and after irradiation.
High voltage CMOS detectors (HVCMOSv3), fabricated in the ams H18 high voltage process, with a substrate resistivity of 10 Omegamiddotcm were irradiated with neutrons up to a fluence of 2 x 10 ...super(16) n sub(eq)/cm super(2) and characterized using edge-TCT. It was found that, within the measured fluence range, the active region and the collected charge reach a maximum at about 7 x 10 super(15) n sub(eq)/cm super(2) to decrease to the level of the unirradiated detector after 2 x 10 super(16) n sub(eq)/cm super(2).
On the timing performance of thin planar silicon sensors Akchurin, N.; Ciriolo, V.; Currás, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2017, Letnik:
859, Številka:
C
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We report on the signal timing capabilities of thin silicon sensors when traversed by multiple simultaneous minimum ionizing particles (MIP). Three different planar sensors, with depletion ...thicknesses 133, 211, and 285µm, have been exposed to high energy muons and electrons at CERN. We describe signal shape and timing resolution measurements as well as the response of these devices as a function of the multiplicity of MIPs. We compare these measurements to simulations where possible. We achieve better than 20ps timing resolution for signals larger than a few tens of MIPs.
Performance of novel silicon n-in-p planar pixel sensors Gallrapp, C.; La Rosa, A.; Macchiolo, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2012, Letnik:
679
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The performance of novel n-in-p planar pixel detectors designed for future upgrades of the ATLAS Pixel system is presented. The n-in-p silicon sensors technology is a promising candidate for the ...pixel upgrade thanks to its radiation hardness and cost effectiveness that allow for enlarging the area instrumented with pixel detectors. The n-in-p modules presented here are composed of pixel sensors produced by CiS connected by bump-bonding to the ATLAS read-out chip FE-I3.
The characterization of these devices has been performed before and after irradiation up to a fluence of 5×1015 1MeVneqcm−2. Charge collection measurements carried out with radioactive sources have proven the functioning of this technology up to these particle fluences. First results from beam test data with a 120GeV/c pion beam at the CERN-SPS are also discussed, demonstrating a high tracking efficiency of (98.6±0.3)% and a high collected charge of about 10ke for a device irradiated at the maximum fluence and biased at 1kV.
Novel silicon n-in-p pixel sensors for the future ATLAS upgrades La Rosa, A.; Gallrapp, C.; Macchiolo, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
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In view of the LHC upgrade phases towards HL-LHC the ATLAS experiment plans to upgrade the inner detector with an all silicon system. The n-in-p silicon technology is a promising candidate for the ...pixel upgrade thanks to its radiation hardness and cost effectiveness that allow for enlarging the area instrumented with pixel detectors.
We present the characterization and performance of novel n-in-p planar pixel sensors produced by CiS (Germany) connected by bump bonding to the ATLAS readout chip FE-I3. These results are obtained before and after irradiation up to a fluence of 10161-MeVneqcm−2, and prove the operability of this kind of sensors in the harsh radiation environment foreseen for the pixel system at HL-LHC. We also present an overview of the new pixel production, which is on-going at CiS for sensors compatible with the new ATLAS readout chip FE-I4.
We have been developing highly radiation-tolerant n+-in-p planar pixel sensors for use in the high-luminosity LHC. Novel n+-in-p structures were made using various combinations of the bias structures ...(punch-through or polysilicon resistor), isolation structures (p-stop or p-spray), and thicknesses (320μm or 150μm). The 1-chip pixel modules with thin FE-I4 pixel sensors were evaluated using test beams, before and after 2×1015neq/cm2 irradiation. The full depletion voltages were estimated to be 44±10V and 380±70V, in the non-irradiated and the irradiated modules, respectively. A reduction of efficiency was observed in the vicinity of the four pixel corners and underneath the bias rail after the irradiation. The global efficiencies were >99% and >95% in the non-irradiated and the irradiated modules, respectively. The collected charges were uniform in the depth direction at bias voltages well above the full depletion voltages. The encapsulation of vulnerable edges with adhesive or parylene prevented HV sparking. Bump bonding with the SnAg solder bumps was performed at HPK with 150μm- and 320μm-thick sensors and chips. No disconnection of bumps was observed after 10 thermal cycles between −40 and +50°C, with a temperature slew rate of >70K/min.
► Novel n+-in-p pixel sensors were made of punch-through/poly-Si biasing, p-stop/p-spray isolation, and 320/150μm thickness. ► The thin pixel modules were evaluated in testbeams, before and after 2×1015neq/cm2 irradiation. ► A reduction of efficiency was observed in the vicinity of four-corners of pixels and underneath the bias rail after irradiation. ► Encapsulating the vulnerable edges with adhesive or parylene achieved prevention of HV sparking up to 1000V. ► No disconnection of SnAg bump-bonds was observed in dummy modules after 10 thermal cycles with a slew rate of >70K/min.
New pixel detector concepts, based on commercial high voltage and/or high resistivity CMOS processes, are being investigated as a possible candidate to the inner and outer layers of the ATLAS Inner ...Tracker in the HL-LHC upgrade. A depleted monolithic active pixel sensor on thick film SOI technology is being extensively investigated for that purpose. This particular technology provides a double well structure, which shields the thin gate oxide transistors from the Buried Oxide (BOX). In addition, the distance between transistors and BOX is one order of magnitude bigger than conventional SOI technologies, making the technology promising against its main limitations, as radiation hardness or back gate effects. Its radiation hardness to Total Ionizing Dose (TID) and the absence of back gate effect up to 700 Mrad has been measured and published 1. The process allows the use of high voltages (up to 300V) which are used to partially deplete the substrate. The process allows fabrication in higher resistivity, therefore a fully depleted substrate could be achieved after thinning. This article shows the results on charge collection properties of the silicon bulk below the BOX by different techniques, in a laboratory with radioactive sources and by edge Transient Current Technique, for unirradiated and irradiated samples.
Various structures for n-in-p planar pixel sensors have been developed at KEK in order to cope with the huge particle fluence in the upcoming LHC upgrades. Performances of the sensors with different ...structures have been evaluated with testbeam. The n-in-p devices were connected by bump-bonding to the ATLAS Pixel front-end chip (FE-I4A) and characterized before and after the irradiation to 1×1016 1MeV neq/cm2. Results of measurements with 120GeV/c momentum pion beam at the CERN Super Proton Synchrotron (SPS) in September 2012 are presented.
•Pixel sensors with two biasing and two isolation structures were evaluated.•Overall hit efficiency of 97.6% was confirmed at −1200V after 1×1016neq/cm2.•Inefficiency regions were observed in non-irradiated samples with P-spray isolation.•Inefficiency regions after high irradiation were observed under bias rail and PolySi.•The potential of the surface structure is thought to affect the charge collection.
A new type of n-in-p planar pixel sensors have been developed at KEK/HPK in order to cope with the maximum particle fluence of 1–3×1016 1MeV equivalent neutrons per square centimeter (neq/cm2) in the ...upcoming LHC upgrades. Four n-in-p devices were connected by bump-bonding to the new ATLAS Pixel front-end chip (FE-I4A) and characterized before and after the irradiation to 2×1015neq/cm2. These planar sensors are 150μm thick, using biasing structures made out of polysilicon or punch-through dot and isolation structures of common or individual p-stop. Results of measurements with radioactive 90Sr source and with a 120GeV/c momentum pion beam at the CERN Super Proton Synchrotron (SPS) are presented. The common p-stop isolation structure shows a better performance than the individual p-stop design, after the irradiation. The flat distribution of the collected charge in the depth direction after the irradiation implies that the effect of charge trapping is small, at the fluence, with the bias voltage well above the full depletion voltage.
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