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Simulated doping concentration as a function of depth for the JTE structure and the gain layer for an implantation dose of 3 · 10 12 cm −3 .
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Low-Gain Avalanche Detectors are gathering interest in the High-Energy Physics community thanks to their fast-timing and radiation-hardness properties. One example of this includes plans to exploit timing detectors for the upgrades of the ATLAS and CMS detectors at the High Luminosity LHC. This new technology has also raised interest for its possib...
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... the contrary, all other implantations are performed at 7 degrees of tilt and 23 of twist to minimize channeling. A SILVACO TCAD [13] simulation is performed to predict the doping profile of the JTE and it is reported in Figure 4. ...
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... these prototypes, the energy is chosen so that the implant is not deeper than the JTE (Figure 2d and Figure 3c). This is visible in Figure 4, where the JTE and the doping concentration of the gain layer are compared. Doses from 2 · 10 12 cm −2 to 3.5 · 10 12 cm −2 have been used to study different gain values. ...
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... these values must be considered as a lower limit, because implantations are retrograde and thus not symmetric: the dose in the silicon on the left of the peak is (slightly) larger than the dose on the right of the peak along the depth x. This can be appreciated in the example of the simulated profiles reported in Figure 4. ...
Citations
... In order to distinguish between the numerous interactions happening within a single bunch crossing at slightly different times, in the order of tens of picoseconds, certain aspects of the present detector technology must be improved, including granularity and read-out speed. This improvement will involve a complete upgrade of the ATLAS inner tracker, along with all its silicon sensors, as part of the transition towards "4D" tracking [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. ...
... In a typical set-up, a trigger sensor with known timing characteristics is aligned with the Device Under Test (DUT) and a radioactive -source (typically 90Sr, which emits electrons with energies of 0.546 MeV and 2.28 MeV) as indicated in figure 11. Typical betas used in the lab have enough energy to be good approximation of MIPs for the first detector only, while they lose more energy in the second -8 - device [1,5,7,8,12,21,23,29,33,35,37,40]. Characterizations at various temperatures was also possible by moving the whole setup inside a cold box. Figure 12 shows a schematic block diagram of the setup prepared at CERN where two sensors (trigger and DUT) have beenmounted and read simultaneously. ...
... However, there are some differences. For example, When it comes to the -14 - creation of electron-hole pairs, the laser beam usually operates within a cylinder with a diameter of approximately 10 μm (depending on the laser optics) but for a MIP, this diameter is considerably smaller, leading to more significant screening effects [1,12,23,24,[37][38][39][40][41][42][43][44][45]. BNL LGADs were used for this study. ...
Low-Gain Avalanche Diodes (LGAD) are the sensor of choice for the timing detectors of the ATLAS and CMS experiments at the High Luminosity Large Hadron Collider (HL-LHC). This paper presents the results of static and dynamic performance evaluations of LGADs manufactured by Hamamatsu Photonics K.K. (HPK) and Brookhaven National Laboratory (BNL). Timing performance was measured using-scopes after a static characterization of the device (current-voltage and capacitance-voltage curves) and a time resolution better than 35 ps was extracted under high operational bias voltage before irradiation. This value is considered within the nominal requirements of the ATLAS project for un-irradiated sensors. Transient Current Technique (TCT) was used to observe and analyze a gain suppression mechanism, i.e. a decrease in gain correlated with increased laser intensities. TCAD simulations were carried out to interpret the gain suppression of the BNL sensors under different conditions of bias voltage and laser intensity. A good correspondence between experimental observations and TCAD simulations was found.
... Currently, a few research facilities around the world are involved in the development of LGADs, such as Brookhaven National Laboratory (BNL, Upton, NY, USA) [7], CNM, Fondazione Bruno Kessler (FBK, Trento, Italy) [8], Hamamatsu (Japan) [9], IHEP-NDL (Beijng, China) [10] and Micron (Lancing, UK) [11]. In addition, read-out electronics are actively being developed. ...
Low-Gain Avalanche Diodes (LGAD) are a class of silicon sensors developed for the fast detection of Minimum Ionizing Particles (MIPs). The development was motivated by the need of resolving piled-up tracks of charged particles emerging from several vertexes originating from the same bunch-crossing in High-Energy Physics (HEP) collider experiments, which, however, are separated not only in space but also in time by a few tens of picoseconds. Built on thin silicon substrates and featuring an internal moderate gain, they provide fast signals for excellent timing performance, which are therefore useful to distinguish the different tracks. Unfortunately, this comes at the price of poor spatial resolution. To overcome this limitation, other families of LGAD-based silicon sensors which can deliver in the same substrate both excellent timing and spatial information are under development. Such devices are, to name a few, capacitively coupled LGADs (AC-LGAD), deep-junction LGADs (DJ-LGAD) and trench-isolated LGADs (TI-LGADs). These devices can be fabricated by even small-scale research-focused clean rooms for faster development within the scientific community. However, to scale up production, efforts towards integrating these sensor concepts in CMOS substrates, with the obvious advantage of the possibility of integrating part of the read-out electronics in the same substrate, have begun.
... The characterization studies of LGAD and AC-LGAD sensors have been performed so far on custom-made test-boards (see for example Refs. [12][13]), designed for the evaluation of a small quantity of sensors. These readout test-boards are based on discrete electronics, by exploiting either low-noise fast trans-impedance or RF amplifiers that closely reproduce the current pulse generated by the sensor. ...
The development of detectors that provide high resolution in four dimensions has attracted wide-spread interest in the scientific community for applications in high-energy physics, nuclear physics, medical imaging, mass spectroscopy as well as quantum information. However, finding a technology capable of fulfilling such aspiration proved to be an arduous task. Among other silicon-based candidates, the Low-Gain Avalanche Diode (LGAD) has already shown excellent timing performances but proved to be unsuitable for fine pixelization. Therefore, the AC-coupled LGAD (AC-LGAD) approach was introduced to provide high resolution in both time and space, making it a promising candidate for future 4D detectors. However, appropriate readout electronics must be developed to match the sensor's fast-time and fine-pitch capabilities. This is currently a major technological challenge. In this paper, we test AC-LGAD prototypes read out by the fast-time ASIC ALTIROC 0, originally developed for the readout of DC-coupled LGADs for the ATLAS experiment at the HL-LHC. Signal generated by either betas from a $^{90}$Sr source or a focused infra-red laser were analyzed. This paper details the first successful readout of an AC-LGAD sensor using a readout chip. This result will pave the way for the design and construction of a new generation of AC-LGAD-based 4D detectors.
... The efficiency of the three-dimensional recording architecture of ToF-MMs is defined by the time-resolving image detector. Delay-line detectors 52,53) or the upcoming solid-state pixel-array detectors 54,55) are characterized by time resolutions in the 50-200 ps range. Hence, for ToF-based experiments not only the pulse length but also the pulse period of the photon source is crucial because the ratio between duration and period determines, how many time slices can be resolved in the time gap between adjacent photon pulses. ...
... The Silicon Low Gain Avalanche Diode (LGAD) has been verified that has better than 50 ps time resolution due to its good S/N between the low gain range (10∼100). And also it has been developed successfully by the various foundries in the past few years [3][4][5][6][7][8][9][10][11]. However, present studies indicate the collected charges of Silicon LGAD decrease rapidly when the irradiation flux up to 2.5×10 15 n eq /cm 2 . ...
Silicon Carbide device (4H-SiC) has potential radiation hardness, high saturated carrier velocity and low temperature sensitivity theoretically. The Silicon Low Gain Avalanche Diode (LGAD) has been verified to have excellent time performance. Therefore, the 4H-SiC LGAD is introduced in this work for application to detect the Minimum Ionization Particles (MIPs). We provide guidance to determine the thickness and doping level of the gain layer after an analytical analysis. The gain layer thickness $d_{gain}=0.5~\mu m$ is adopted in our design. We design two different types of 4H-SiC LGAD which have two types electric field, and the corresponding leakage current, capacitance and gain are simulated by TCAD tools. Through analysis of the simulation results, the advantages and disadvantages are discussed for two types of 4H-SiC LGAD.
... The Centro Nacional de Microelectrónica (CNM) Barcelona made the first developments and measurements with LGAD sensors [2], which have been followed by many others [3,4,5,6,7]. The key property of an LGAD sensor is a gain layer (at n ++ /p + junction) that is carefully tuned to give sufficient gain at moderate voltages at which the active thickness of the LGAD can be depleted to achieve high drift velocities. ...
The low gain avalanche detectors (LGADs) are thin sensors with fast charge collection which in combination with internal gain deliver an outstanding time resolution of about 30 ps. High collision rates and consequent large particle rates crossing the detectors at the upgraded Large Hadron Collider (LHC) in 2028 will lead to radiation damage and deteriorated performance of the LGADs. The main consequence of radiation damage is loss of gain layer doping (acceptor removal) which requires an increase of bias voltage to compensate for the loss of charge collection efficiency and consequently time resolution. The Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS) has developed a process based on the Institute of Microelectronics (IME), CAS capability to enrich the gain layer with carbon to reduce the acceptor removal effect by radiation. After 1 MeV neutron equivalent fluence of 2.5$\times$10$^{15}$ n$_{eq}$/cm$^{2}$, which is the maximum fluence to which sensors will be exposed at ATLAS High Granularity Timing Detector (HGTD), the IHEP-IME second version (IHEP-IMEv2) 50 $\mu$m LGAD sensors already deliver adequate charge collection > 4 fC and time resolution < 50 ps at voltages < 400 V. The operation voltages of these 50 $\mu$m devices are well below those at which single event burnout may occur.
... To enhance performance and lifetime, most of the silicon-based detectors also need an expensive cooling system, which makes the overall detector system giant and expensive. Alternative diamond detectors have been investigated with high radiation hardness up to 3 × 10 15 particles/cm 2 [3] and have been successfully used in the ATLAS experiment at the LHC [4]. However, they are also characterized by high cost and a difficult doping process in diamond, which limit their application. ...
... A time resolution better than 20 ps has been achieved in silicon planar sensors with depletion thicknesses 133-285 μm for multiple MIP signals [11], whereas 100 μm silicon pixel detectors with 800 μm × 800 μm size have achieved a time resolution of 106 ps [12]. Currently, 50 μm silicon detectors with internal gain, usually referred to as Low Gain Avalanche Detector (LGAD), are developed by various foundries and show a time resolution of at least 50 ps [13][14][15][16][17][18]. The 4H-SiC detectors also show fast time response, coming from the highly saturated carrier velocity, but no time performance study has been reported so far. ...
We address the determination of the time resolution for the 100 μm 4H-SiC PIN detectors fabricated by Nanjing University (NJU). The time response to β particles from a ⁹⁰ Sr source is investigated for the detection of the minimum ionizing particles (MIPs). We study the influence of different reverse voltages, which correspond to different carrier velocities and device sizes, and how this correlates with the detector capacitance. We determine a time resolution (94 ± 1) ps for a 100 μm 4H-SiC PIN detector. A fast simulation software, termed RASER (RAdiation SEmiconductoR), is developed and validated by comparing the waveform obtained from simulated and measured data. The simulated time resolution is (73 ± 1) ps after considering the intrinsic leading contributions of the detector to time resolution.
... One of the major breakthroughs in detector technology in recent years has been the development of novel types of silicon detectors that provide good timing resolution. These detectors are based on technologies that have demonstrated timing resolution of few tens of picoseconds, for instance with Low Gain Avalanche Detectors (LGADs) [2] [3]. Developed for the High Luminosity LHC (HL-LHC) experiments, conventional ...
We present measurements of AC-LGADs performed at the Fermilab's test beam facility using 120 GeV protons. We studied the performance of various strip and pad AC-LGAD sensors that were produced by BNL and HPK. The measurements are performed with our upgraded test beam setup that utilizes a high precision telescope tracker, and a simultaneous readout of up to 7 channels per sensor, which allows detailed studies of signal sharing characteristics. These measurements allow us to assess the differences in designs between different manufacturers, and optimize them based on experimental performance. We then study several reconstruction algorithms to optimize position and time resolutions that utilize the signal sharing properties of each sensor. We present a world's first demonstration of silicon sensors in a test beam that simultaneously achieve better than 5-10 micron position and 30 ps time resolution. This represents a substantial improvement to the spatial resolution than would be obtained with binary readout of sensors with similar pitch.
... The efficiency of the three-dimensional recording architecture of ToF-MMs (and angular-resolving ToF spectrometers 89,90 ) is defined by the time-resolving image detector. Delay-line detectors 91,92 or the upcoming solid-state pixel-array detectors 93,94 are characterized by time resolutions in the 50-200 ps range. Hence, for ToF-based experiments not only the pulse length but also the pulse period of the photon source is crucial because the ratio between duration and period determines, how many time slices can be resolved in the time gap between adjacent photon pulses. ...
... In contrast, if the limitation is the maximum detectable count rate of the detector for those cases where the incident photon flux sets no limit, it will be equivalent whether the huge data array is filled sequentially or by parallel recording of a momentum and energy interval. Detector schemes with high degree of parallelization based on the delay-line principle 91,92 or pixelated solid-state detectors 93,94 will push the count-rate limit so that the detector will not be the bottleneck of the total recording efficiency. ...
Momentum microscopy (MM) is a novel way of performing angular-resolved photoelectron spectroscopy (ARPES). Combined with time-of-flight (ToF) energy recording, its high degree of parallelization is advantageous for photon-hungry experiments like ARPES at X-ray energies and spin-resolved ARPES. This article introduces into the spin-resolved variant of ToF-MM and illustrates its performance by selected examples obtained in different spectral ranges. In a multidimensional view of the photoemission process, spectral density function D(k,EB), spin polarization P(k,EB) and related quantities of circular dichroism in the angular distribution (CDAD) are part of the complete experiment, a concept adopted from atomic photoemission. We show examples of spin-resolved valence-band mapping in the UV, VUV, soft- and hard-X-ray range. Spin mapping of the Heusler compounds Co2MnGa and Co2Fe0.4Mn0.6Si at hn=6eV prove that the second compound is a half-metallic ferromagnet. Analysis of the Tamm state on Re(0001) using VUV-excitation reveals a Rashba-type spin texture. Bulk band structure including Fermi surface, Fermi velocity distribution vF(k,EF), full CDAD texture and spin signature of W(110) have been derived via tomographic mapping with soft X-rays. Hard X-rays enable accessing large kpar-regions so that the final-state sphere crosses many Brillouin zones in k-space with different kz. At hn=5.3keV this fast 4D mapping mode (at fixed hn) revealed the temperature dependence of the Fermi surface of the Kondo system YbRh2Si2. Probing the true bulk spin polarization of Fe3O4 at hn=5keV proved its half-metallic nature. As an outlook, the emerging method of ToF-MM with fs X-ray pulses from a free-electron laser demonstrates the potential of simultaneous valence, core-level and photoelectron diffraction measurements in the ultrafast regime.
... To separate collisions in limited space, the choice of solid state timing detectors for ATLAS High Granularity Timing Detector (HGTD) project [2] are presently thin Low Gain Avalanche Detectors(LGAD) [3,4], which have timing resolution better than 50ps. So far the LGAD sensors have been developed by several silicon foundries and institutes including HPK [5], FBK [6], CNM [3], BNL [7], NDL [8,9,10,11]. The Institute of High Energy Physics (IHEP) High-Granularity Timing Detector group has recently developed IHEP-IME LGAD (IHEP-IMEv1) sensors with the Institute of Microelectronics (IME) of the Chinese Academy of Sciences [12], which are aimed to be used as sensors for the HGTD project. ...
This paper will show the simulation and testing results of 50{\mu}m thick Low Gain Avalanche Detectors (LGAD) sensors designed by the Institute of High Energy Physics (IHEP) and fabricated by the Institute of Micro Electronics (IME) of Chinese Academy of Sciences. Testing results show that the IHEP-IME sensors with higher dose for gain layer have lower breakdown voltages and higher gain layer voltage for capacitance-voltage properties, which are consistent with the TCAD simulation results. Beta testing results show that the time resolution of IHEP-IME sensors are better than 35ps and the collected charges of IHEP-IME sensors are larger than 15fC before irradiation, which fulfill the required specifications of sensors before irradiations for ATLAS HGTD project.
