Radiation damage effects at High Luminosity LHC (HL-LHC) expected fluences and total ionizing doses (TID) will impose very stringent constraints in terms of radiation resistance of silicon detectors. ...In this work, we address the effects of surface damage on detectors fabricated on p-type substrates by two different foundries. Starting from standard test structure measurements, the interface trap state density and the oxide charge can be extracted for each specific foundry before and after irradiation with X-rays with doses ranging from 0.05 to 100 Mrad(SiO2). These parameters are then used as inputs to the Technology-CAD simulation tools, aiming at evaluating the effects of oxide charge density and interface trap density variation with the dose on MOS capacitor capacitances and interstrip resistances. The good agreement between simulation results and measurements would support the use of the model as a predictive tool to optimize the design and the operation of novel silicon detectors in the HL-LHC scenario.
This paper presents the results from the crosstalk and dark count rate (DCR) characterization of a 24 × 72 single photon avalanche diode (SPAD) array, fabricated in a 150 nm CMOS technology. The chip ...under test consists of a dual layer detection system developed in view of applications to charged particle tracking. A three step procedure, used for the crosstalk characterization, is presented. The crosstalk probability, taking place in 5 × 5 sub arrays built around noisy pixels, has been computed. Eventually, random telegraph signal (RTS) fluctuations in DCR, at different bias conditions, are briefly discussed.
Monolithic Active Pixel Sensors (MAPS) represent one of the most promising technologies for the next generation of radiation detectors. The ARCADIA project aims at the development of Fully Depleted ...(FD) MAPS employing a production process compatible with a 110 nm commercial CMOS technology. The first engineering run of the project included matrices of active pixels with embedded analog and digital frontend electronics and passive test structures such as passive pixel arrays, MOS capacitors and backside diodes. Although the produced samples were already characterized from the electrical point of view, a thorough study of the charge collection dynamics of the passive pixel arrays was still missing. In this paper we show the results of the dynamic characterization of a group of passive pixel arrays with different pixel pitches (50, 25 and 10
μ
m) and different pixel layouts. The tested samples have been illuminated from the backside with an infrared and a red laser with wavelengths equal to 1,060 nm and 660 nm, respectively. The pixel arrays have been mounted on a custom readout PCB connected to an external amplifier with 1 GHz bandwidth and the signals have been acquired through a fast digital oscilloscope. We employed both focused and unfocused laser spots to evaluate the change in the measured signal as a function of the laser spot position and the average response of the pixel arrays. An excellent agreement has been demonstrated by comparing the measured signals with the results of transient TCAD simulations and a time for 50% charge collection of 7.8, 4.2 and 2.6 ns has been predicted and experimentally validated in pixels with 50, 25 and 10
μ
m pitch, respectively.
In this paper, we present the implementation and preliminary evaluation of a new type of silicon sensor for charged particle detection operated in Geiger-mode. The proposed device, formed by two ...vertically-aligned pixel arrays, exploits the coincidence between two simultaneous avalanche events to discriminate between particle-triggered detections and dark counts. A proof-of-concept two-layer sensor with per-pixel coincidence circuits was designed and fabricated in a 150nm CMOS process and vertically integrated through bump bonding. The sensor includes a 48×16pixel array with 50μm×75μm pixels. This work describes the sensor architecture and reports a selection of results from the characterization of the avalanche detectors in the two layers. Detectors with an active area of 43×45μm2 have a median dark count rate of 3kHz at 3.3V excess bias and a breakdown voltage non-uniformity lower than 20mV.
The basic principle of operation of silicon sensors with resistive read-out is built-in charge sharing. Resistive Silicon Detectors (RSD, also known as AC-LGAD), exploiting the signals seen on the ...electrodes surrounding the impact point, achieve excellent space and time resolutions even with very large pixels. In this paper, a TCT system using a 1064 nm picosecond laser is used to characterize RSD sensors produced by Fondazione Bruno Kessler. The paper first introduces the parametrization of the errors in the determination of the position and time coordinates in RSD, then outlines the reconstruction method, and finally presents the results. Three different pixel pitches are used in the analysis: 200 × 340, 450 × 450, and 1300 × 1300 μm2. At gain = 30, the 450 × 450 μm2 pixel achieves a time jitter of 20 ps and a spatial resolution of 15 μm concurrently, while the 1300 × 1300 μm2 pixel achieves 30 ps and 30 μm, respectively. The implementation of cross-shaped electrodes improves considerably the response uniformity over the pixel surface.
This paper presents the measurements on first very thin Ultra-Fast Silicon Detectors (UFSDs) produced by Fondazione Bruno Kessler; the data have been collected in a beam test setup at the CERN PS, ...using beam with a momentum of 12 GeV/c. UFSDs with a nominal thickness of 25 and 35
μ
m and an area of 1
×
1
mm
2
have been considered, together with an additional HPK 50-
μ
m thick sensor, taken as reference. Their timing performances have been studied as a function of the applied voltage and gain. A time resolution of about 25 ps and of 22 ps at a voltage of 120 and 240 V has been obtained for the 25 and 35
μ
m thick UFSDs, respectively.
An array of Single Photon Avalanche Diodes (SPAD), fabricated in a 180 nm CMOS technology featuring a high voltage (HV) option, has been investigated in terms of radiation tolerance, in view of the ...design of low material budget dual-tier detectors for charged particle tracking based on the coincidence of signals coming from pairs of vertically aligned pixels. Each pixel in the array includes both the processing electronics and the sensing element in a monolithic structure. The test vehicles were irradiated with 10 keV X-rays up to a dose of 1 Mrad (SiO2) and with neutrons up to a fluence of 1011 neq cm−2. A selection of the characterization results are presented together with the main features of a new large scale SPAD array to be fabricated in a 150 nm CMOS technology and ready for vertical interconnection in a dual layer structure.
•Characterization of SPADs in a 180 nm CMOS technology.•Radiation tolerance evaluation involving ionizing and non-ionizing sources.•Design features of a new charged particle detector based on 150 nm CMOS SPADs in a dual-layer structure.
In this paper we present a position-sensitive detector based on the vertical integration of pairs of aligned pixels operating in Geiger-mode regime and designed for charged particle detection. This ...novel device exploits the coincidence between two simultaneous avalanche events to discriminate between particle-triggered detections and dark counts. This concept allows to have a reduced material budget and low power consumption in spite of a high granularity and fast timing response. A proof-of-principle prototype was designed and fabricated in a 150 nm CMOS process and vertically integrated through bump bonding. This first demonstrator has been characterized and tested with a high energy particle beams at CERN SPS/PS facilities, in different configurations, featuring a reduction of the dark-count rate (DCR) at room temperature from ∼100 kHz/mm2 to about 24 Hz/mm2 a particle detection efficiency limited only by the geometric factor. The device radiation tolerance has been investigated, via irradiation of single tiers with 10 keV X-rays up to a dose of 1 Mrad (SiO2) and with neutrons up to a fluence of 1011 cm−2. A second prototype, addressing the goal to improve the present fill-factor, has been designed, manufactured and approaches now the characterization phase. Potential applications of this sensor include high spatial resolution tracking in high-energy experiments, radiation monitoring in space and radiation imaging in nuclear medicine. A small hand-held demonstrator is under construction for radio-guided surgery.
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