Type inversion in irradiated silicon: a half truth
M. Swartz, D. Bortoletto, V. Chiochia, L. Cremaldi, S. Cucciarelli, A. Dorokhov, M. Konecki, K. Prokofiev, C. Regenfus, T. Rohe, D. A. Sanders, S. Son, T. Speer
备注：
18 pages, LaTeX document, 11 figures, version 2 fixes small typos
Charge collection measurements performed on heavily irradiated p-spray dofz pixel sensors with a grazing angle hadron beam provide a sensitive determination of the electric field within the detectors. The data are compared with a complete charge transport simulation of the sensor which includes signal trapping and charge induction effects. A linearly varying electric field based upon the standard picture of a constant type-inverted effective doping density is inconsistent with the data. A two-trap double junction model implemented in ISE TCAD software can be tuned to produce a doubly-peaked electric field which describes the data reasonably well at two different fluences. The modeled field differs somewhat from previous determinations based upon the transient current technique. The model can also account for the level of signal trapping observed in the data.
In this paper the results of a beam test characterization campaign of 3D trench silicon pixel sensors are presented. A time resolution in the order of 10 ps was measured both for non-irradiated and irradiated sensors up to a fluence of $2.5 \cdot 10^{16}\,1\,MeV\, n_{eq}\,cm^{-2}$. This feature and a detection efficiency close to $99\%$ make this sensors one of the best candidates for 4D tracking detectors in High-Energy-Physics experiments.
Planar silicon pixel sensors with modified n$^+$-implantation shapes based on the IBL pixel sensor were designed in Dortmund. The sensors with a pixel size of $250\,μ$m $\times$ $50\,μ$m are produced in n$^+$-in-n sensor technology. The charge collection efficiency should improve with electrical field strength maxima created by the different n$^+$-implantation shapes. Therefore, higher particle detection efficiencies at lower bias voltages could be achieved. The modified pixel designs and the IBL standard design are placed on one sensor to test and compare the designs. The sensor can be read o…
Capacitance-voltage (CV) measurements are a widely used technique in silicon detector physics. It gives direct information about the full depletion voltage and the effective doping concentration. However, for highly irradiated sensors, the measured data differs significantly from the usual shape which makes the extraction of the afore mentioned parameters less precise to not possible. We present an explanation for the obseved frequency dependence and based on that, a method to extract the desired sensor parameters.
The value of the scaling parameter $E_{\text{eff}}$ of the temperature dependence for current generated in silicon bulk is investigated for highly irradiated devices. Measurements of devices irradiated to fluences above $1 \times 10^{15} n_{\text{eq}} \text{cm}^{-2} $ have shown a different temperature scaling behaviour than devices irradiated to lower fluences. This paper presents the determination of the parameter $E_{\text{eff}}$ for diodes irradiated with protons up to fluences of $3 \times 10^{15} n_{\text{eq}} \text{cm}^{-2}$ in the bias range from $0$V to $1000$V at temperatures from $-…
The understanding of the weighting field of irradiated silicon sensors is essential for calculating the response of silicon detectors in the radiation environment at accelerators like at the CERN LHC. Using 1-D calculations of non-irradiated pad sensors and 1-D TCAD simulations of pad sensors before and after irradiation, it is shown that the time-dependence of the weighting field is related to the resistivity of low field regions with ohmic behaviour in the sensor. A simple formula is derived, which relates the time constant of the time-dependent weighting field, $τ$, with the resistivity and…
The high-luminosity operation of the Tracker in the Compact Muon Solenid (CMS) detector at the Large Hadron Collider (LHC) experiment calls for the development of silicon-based sensors. This involves implementation of AC-coupling to micro-scale pixel sensor areas to provide enhanced isolation of radiation-induced leakage currents. The motivation of this study is the development of AC-pixel sensors with negative oxides (such as aluminium oxide - Al$_2$O$_3$ and hafnium oxide - HfO$_2$) as field insulators that possess good dielectric strength and provide radiation hardness. Thin films of Al$_2$…
A method is presented which allows to obtain the position-dependent electric field and charge density by fits to velocity profiles from edge-TCT data from silicon strip-detectors. The validity and the limitations of the method are investigated by simulations of non-irradiated $n^+p$ pad sensors and by the analysis of edge-TCT data from non-irradiated $n^+p$ strip-detectors. The method is then used to determine the position dependent electric field and charge density in $n^+p$ strip detectors irradiated by reactor neutrons to fluences between 1 and $10 \times 10^{15}$ cm$^{-2}$ for forward-bias…
Background: Edge-on-irradiated silicon detectors are currently being investigated for use in photon-counting CT applications. The low atomic number of silicon leads to a significant number of incident photons being Compton scattered in the detector, depositing a part of their energy and potentially being counted multiple times. Although the physics of Compton scatter is well established, the effects of Compton interactions in the detector on image quality for an edge-on-irradiated silicon detector have still not been thoroughly investigated. Purpose: To investigate and explain effects of Compt…
The ATLAS experiment at the LHC will replace its current inner tracker system for the HL-LHC era. 3D silicon pixel sensors are being considered as radiation-hard candidates for the innermost layers of the new fully silicon-based tracking detector. 3D sensors with a small pixel size of $\mathrm{50 \times 50~μm^{2}}$ and $\mathrm{25 \times 100~μm^{2}}$ compatible with the first prototype ASIC for the HL-LHC, the RD53A chip, have been studied in beam tests after uniform irradiation to $\mathrm{5 \times 10^{15}~n_{eq}/cm^{2}}$. An operation voltage of only 50 V is needed to achieve a 97% hit effic…
High-energy physics detectors, like Low Gain Avalanche Detectors (LGADs) that will be used as fast timing detectors in the High Luminosity LHC experiments, have to exhibit a significant radiation tolerance. Thereby the impact of radiation on the highly boron-doped gain layer that enables the internal charge multiplication, is of special interest, since due to the so-called Acceptor Removal Effect (ARE) a radiation-induced deactivation of active boron dopants takes place. In this paper we present defect-spectroscopy measurements (Deep-Level Transient Spectroscopy and Thermally Stimulated Curren…
Temperature dependence of the long-term annealing behavior of neutron irradiated diodes from 8-inch p-type silicon wafers
CERN（欧洲核子研究组织）；Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；Heidelberg University（海德堡大学）；Uppsala University（乌普萨拉大学）；Al-Farabi Kazakh National University（阿尔法拉比哈萨克国立大学）；An Najah National University（安纳贾赫国立大学）；HAN University of Applied Sciences（汉应用科学大学）
In the future ATLAS Inner Tracker, each silicon strip module will be equipped with a switch able to separate the high voltage supply from the sensor in case the latter becomes faulty. The switch, placed in between the HV supply and the sensor, needs to sustain a high voltage in its OFF state, to offer a low resistance path for the sensor leakage current in the ON state, and be radiation hard up to 1.2e15 neq/cm2 along with other requirements. While GaN JFETs have been selected as suitable rad-hard switch, a silicon vertical HV-JFET was developed by Brookhaven National Laboratory as an alternat…
We are investigating the feasibility of using CMOS foundries to fabricate silicon detectors, both for pixels and for large-area strip sensors. The availability of multi-layer routing will provide the freedom to optimize the sensor geometry and the performance, with biasing structures in poly-silicon layers and MIM-capacitors allowing for AC coupling. A prototyping production of strip test-structures and RD53A compatible pixel sensors was recently completed at LFoundry in a 150$\,$nm CMOS process. This paper will focus on the characterization of irradiated and non-irradiated pixel modules, comp…
The absorption length, $λ_{abs}$, of light with wavelengths between 0.95 and 1.30$~μ$m in silicon irradiated with 24$~$GeV/c protons to 1$~$MeV neutron equivalent fluences between 0 and $8.6 \times 10^{15}~$cm$^{-2}$ has been measured. It is found that $λ_{abs}$ decreases with fluence due to radiation-induced defects. A phenomenological parametrisation of the radiation-induced change of $λ_{abs}$ as a function of wavelength and neutron equivalent fluence at room temperature is given. The observation of the decrease of $λ_{abs}$ with irradiation is confirmed by edge-TCT measurements on irradiat…
Within CERN RD50 Collaboration, MCz Si was identified as a best material for the detector used in the high luminosity collider experiments. The n in p Si detectors were utmost radiation hard detectors, which can be used for the phase 2 upgrade plan of the new Compact Muon Solenoid tracker detector in 2026. The choice of n or p-MCz Si material depends upon the high electrical charge collection efficiency performance of these detectors over n or p-FZSi detectors. The bulk radiation damage model for n, p-MCz Si need to develop for the designing, development and optimization of the advanced detect…
The unique electrical and material properties of 4H-silicon-carbide (4H-SiC) make it a promising candidate material for high rate particle detectors. In contrast to the ubiquitously used silicon (Si), 4H-SiC offers a higher carrier saturation velocity and larger breakdown voltage, enabling a high intrinsic time resolution and mitigating pile-up effects. Additionally, as radiation hardness requirements grow more demanding, wide-bandgap materials such as 4H-SiC could offer better performance. In this work, the detector performance of 50 micron thick 4H-SiC p-in-n planar pad sensors was investiga…
The current understanding of radiation tollerance of Silicon Photomultipliers (SiPMs) is reviewd. Radiation damage in silicon sensors is briefly introduced, surface and bulk effects are separately addressed. Results on the operation of irradiated SiPMs with X-ray, gamma, electron, proton and neutron sources are presented. The most critical effect of radiation on SiPMs is the increase of dark count rate, which makes it impossible to resolve signals generated by a single photon from the noise. Methods to characterize irradiated SiPMs after their single photo-electron resolution is lost are discu…
Optimization of various isolation techniques to develop low noise, radiation hard double-sided silicon strip detectors for the CBM Silicon Tracking System
本文报道了双面硅微条探测器（DSSD）的设计优化，以减少等效噪声电荷（ENC），并最大限度地提高击穿电压和电荷收集效率。各种隔离技术进行了探讨，并进行了详细的比较研究，以优化检测器的性能。为了评价硅探测器的性能，已包括辐射损伤模型。在五年的预期CBM运行期间，预计中子注量为每年2 × 10 ^{13} n_{eq} cm $^{-2}$，中间阶段为热维护、冷维护和停堆。已经进行了瞬态模拟，以估计辐照探测器的电荷收集性能和模拟已与实验数据进行了验证。
The replacement of the existing endcap calorimeter in the Compact Muon Solenoid (CMS) detector for the high-luminosity LHC (HL-LHC), scheduled for 2027, will be a high granularity calorimeter. It will provide detailed position, energy, and timing information on electromagnetic and hadronic showers in the immense pileup of the HL-LHC. The High Granularity Calorimeter (HGCAL) will use 120-, 200-, and 300-$μ\textrm{m}$ thick silicon (Si) pad sensors as the main active material and will sustain 1-MeV neutron equivalent fluences up to about $10^{16}~\textrm{n}_\textrm{eq}\textrm{cm}^{-2}$. In order…
A study of 3D pixel sensors of cell size 50 μm x 50 μm fabricated at IMB-CNM using double-sided n-on-p 3D technology is presented. Sensors were bump-bonded to the ROC4SENS readout chip. For the first time in such a small-pitch hybrid assembly, the sensor response to ionizing radiation in a test beam of 5.6 GeV electrons was studied. Results for non-irradiated sensors are presented, including efficiency, charge sharing, signal-to-noise, and resolution for different incidence angles.
Signal and noise of Diamond Pixel Detectors at High Radiation Fluences
CVD金刚石由于其大的带隙和强的晶格结构而具有很强的抗辐射性，是LHC顶点探测器的一种有吸引力的材料选择。特别地，在相互作用点附近操作的像素检测器受益于金刚石的微小漏电流和小像素电容，从而与硅相比具有低噪声系数。另一方面，来自穿越高能粒子的电荷信号在金刚石中比在硅中小约2.2倍。因此，在超过10 $^{15}$ n $_{eq}$ cm $^{-2}$的注量下，与硅相比，定量测定金刚石的信噪比（S/N）是重要的，这是LHC升级所期望的。基于对辐照金刚石传感器的测量和FE-I4像素读出芯片的设计，我们确定了高粒子注量辐照金刚石像素探测器的信号和噪声。为了表征辐射损伤对材料和信号降低的影响，将载流子的平均自由程$λ_{e/h}$的变化确定为辐射通量的函数。我们利用为ATLAS升级开发的FE-I4像素芯片来实际估计预期的噪声系数：给定通量下的预期漏电流来自校准计算，像素电容使用专门开发的芯片（PixCap）测量。我们比较所得的S/N数字与平面硅像素探测器使用公布的电荷损失测量和相同的外推方法，为金刚石。它示出，预期的S/N的金刚石像素探测器与像素间距典型的LHC，超过平面硅像素在超过10 $^{15}$粒子cm $^{-2}$的注量，确切的值仅取决于最大的操作电压假设为辐照硅像素探测器。
Testbeam studies of pre-prototype silicon strip sensors for the LHCb UT upgrade project
LHCb实验正准备在2018-2019年进行重大升级。升级的关键组件之一是位于实验分析磁体上游的新硅跟踪器。上游跟踪器（UT）将由硅条探测器的四个平面组成，每个平面覆盖约2 m $^2$的面积。这些探测器的一个重要考虑因素是它们在暴露于大辐射剂量后的性能。在这篇文章中，我们提出了预原型的n-in-p和p-in-n传感器，已被照射的能量密度高达$4.0\times10^{14}$ $n_{\rm eq}$ cm $^{-2}$的测试束结果。
HV-CMOS pixel sensors are a promising option for the tracker upgrade of the ATLAS experiment at the LHC, as well as for other future tracking applications in which large areas are to be instrumented with radiation-tolerant silicon pixel sensors. We present results of testbeam characterisations of the $4^{\mathrm{th}}$ generation of Capacitively Coupled Pixel Detectors (CCPDv4) produced with the ams H18 HV-CMOS process that have been irradiated with different particles (reactor neutrons and 18 MeV protons) to fluences between $1\cdot 10^{14}$ and $5\cdot 10^{15}$ 1-MeV-n$_\textrm{eq}$/cm$^2$. T…
A significant aspect of the Phase-II Upgrade of the ATLAS detector is the replacement of the current Inner Detector with the ATLAS Inner Tracker (ITk). The ATLAS ITk is an all-silicon detector consisting of a pixel tracker and a strip tracker. Sensors for the ITk strip tracker have been developed to withstand the high radiation environment in the ATLAS detector after the High Luminosity Upgrade of the Large Hadron Collider at CERN, which will significantly increase the rate of particle collisions and resulting particle tracks. During their operation in the ATLAS detector, sensors for the ITk s…
Radiation effects on surface and bulk properties of ATLAS18 silicon sensors under low- and high-dose gamma irradiation and annealing
Institute of Physics, Academy of Sciences of the Czech Republic（捷克科学院物理研究所）；Santa Cruz Institute for Particle Physics (SCIPP)（圣克鲁斯粒子物理研究所）；UJP Praha a.s.（UJP布拉格有限公司）；Experimental Particle Physics Department, Jožef Stefan Institute（约瑟夫斯特凡研究所实验粒子物理部）；Instituto de Microelectronica de Barcelona (IMB-CNM), CSIC（西班牙国家科学研究委员会巴塞罗那微电子研究所）；Institute of Particle and Nuclear Study, High Energy Accelerator Research Organization (KEK)（高能加速器研究机构粒子核研究部）；Physikalisches Institut, Albert-Ludwigs-Universität Freiburg（弗赖堡大学物理研究所）
