The 40th RD50 Workshop (CERN)

21 Jun 2022, 08:45 → 24 Jun 2022, 17:00 Europe/Zurich

6/2-024 - BE Auditorium Meyrin (CERN)

Esteban Curras Rivera (CERN), Anja Himmerlich (CERN), Michael Moll (CERN)

40th RD50 Workshop on Radiation hard semiconductor devices for very high luminosity colliders

Tuesday, 21 June

09:00 → 12:50 Defect and Material Characterization

09:00 Welcome

Speaker: Michael Moll (CERN)

220621-RD50-Welcome_v0.pdf

220621-RD50-Welcome_v0.pptx

09:10 Non-Ionizing Energy Loss: Geant4 simulations and OPTICS clustering towards more advanced NIEL concept for radiation damage modelling and prediction

The Non Ionizing Energy Loss (NIEL) concept compares and scales the damage impacted on semiconductor devices in different radiation fields. A particular weakness of the present NIEL concept consists in the inability to predict the different formation rates of cluster and point defects in the silicon (Si) crystal for different particles and particle energies. Specifically, differences between radiation damage produced by neutrons and protons of the same displacement energies (i.e. damage parameters
normalized to the NIEL) has been observed experimentally. In previous RD50 contribution the interactions of neutrons and protons of different energies in a 100 um thick Si target were studied and the kinematics of the Primary Knock-on Atoms (PKA) has been characterized. In this work, we present subsequent silicon cascade studies.
A full Si cascade is simulated in Geant4 and results are further proceeded by an OPTICS (Ordering points to identify the clustering structure) algorithm. The dependency of the isolated vs clustered defects ratio along with the cluster sizes and quantities is explored as a function of Si-recoil energy.

Speaker: Vendula Subert (Hamburg University (DE))

RD50_Subert(2).pdf

RD50_Subert(2).pptx

RD50_Subert.pdf

09:30 Radiation damage investigation of epitaxial p-type silicon using DLTS and TAS measurements of Schottky and pn-junction diodes

This project focuses on the investigation of trap energy levels introduced by radiation damage in epitaxial p-type silicon. Using 6-inch wafers of various boron doping concentrations (1e13, 1e14, 1e15, 1e16, and 1e17 cm-3) with a 50 µm epitaxial layer, multiple iterations of test structures consisting of Schottky and pn-junction diodes of different sizes and flavours are being fabricated at RAL and Carleton University.

In this talk, details on the diode fabrication and electrical measurements of the structures will be given. IV and CV scans of fabricated test structures have been performed and cross-checked between institutes, the results of which will be presented. The focus will be on the characterisation of trap parameters obtained from Deep-Level Transient Spectroscopy (DLTS) and supplemented by Thermal Admittance Spectroscopy (TAS). Spectra for various unirradiated diode samples will be shown and their details collected from Arrhenius analyses will be listed.

Finally, the on-going activities for the next round of wafer processing will be reviewed and an outlook for the detailed testing of irradiated diode samples in the coming months will be given.

Speaker: Christoph Thomas Klein (Carleton University (CA))

2022-06-21_RD50_Workshop.pdf

09:50 Update on Radiation damage investigation of epitaxial P-type Silicon using Schottky diodes

This project focuses on the investigation of radiation damage of epitaxial P-type silicon.

Various test structures consisting of Schottky diodes and p junctions of different sizes and flavors have been fabricated at different facilities, including RAL and Carleton University.

The structures are fabricated on 6 inch wafers of various doping (1e13, 1e14, 1e15, 1e16, and 1e17 B cm-3) and 50 um thick epitaxial layer.

Test updates on the second batch of fabricated Schottky devices at RAL with high and medium resistivity wafers will be given. IV in the reverse and forward region, along with CV measurements of non-irradiated and n-irradiated devices will be shown.

Charge collection test results of irradiated and non-irradiated devices, using an improved laser system that allows testing at temperature down to -20 C will be shown. Details of the Laser setup will be given.

Update on TCAD scripts for the simulation of the devices will be presented as well.

Speaker: Dr Matthew Glenn Kurth (Institute of High Energy Physics (CN))

Kurth_Schottky_40rd50.pdf

10:10 The A_Si-Si_i-defect - a possible candidate to explain acceptor removal in LGADs

Experimental evidence for the explanation of light-induced degradation (LID) in silicon by the A_Si-Si_i-defect is summarized [1, 2]. Based on these findings, a possible involvement of the B_Si-Si_i-defect in the acceptor removal phenomenon of low-gain avalanche detectors (LGAD) [3] with a boron-doped gain layer is discussed. An outlook on density functional theory (DFT) based calculations of the A_Si-Si_i-defect configurations and energy barriers in-between is given.

[1] K. Lauer, C. Möller, D. Schulze, and C. Ahrens, “Identification of photoluminescence P line in indium doped silicon as InSi-Sii defect,” AIP Advances, vol. 5, no. 1, p. 017101, Jan. 2015, doi: 10.1063/1.4905066.
[2] K. Lauer, C. Möller, C. Tessmann, D. Schulze, and N. V. Abrosimov, “Activation energies of the InSi-Sii defect transitions obtained by carrier lifetime measurements,” physica status solidi (c), vol. 14, no. 5, p. 1600033, 2017.
[3] K. Lauer, K. Peh, S. Krischok, S. Reiß, E. Hiller, and T. Ortlepp, “Development of low gain avalanche detectors (LGAD) in frame of the acceptor removal phenomenon,” physica status solidi (a), doi: 10.1002/pssa.202200177.

Speaker: Dr Kevin Lauer (CiS Institut fuer Mikrosensorik GmbH (DE) / TU Ilmenau (DE))

220621_ASiSii_40thRD50.pdf

10:30 Coffee break

11:00 Investigation of high resistivity p-type FZ silicon diodes after 60Co - gamma irradiation

In this work, the macroscopic (I-V, C-V) and microscopic (Thermally Stimulated Current(TSC) and Capacitance(TS-Cap)) measurements were used to investigate the properties of high resistivity p-type diodes irradiated with 60Co gamma-rays with dose values of 10, 20, 100 and 200 Mrad. Two types of diodes are manufactured using p-stop and p-spray to isolate pad and guard ring, and both are FZ p-type materials. For macroscopic measurements, frequency-dependent C-V only appeared on p-stop diodes and presented strongly dose-dependence; The development of leakage current density (jd) with dose value was investigated. Compared to standard FZ n-type diodes, the exponential increase of jd with dose didn’t appear. In the microscopic measurements, the development of irradiation-induced defects concentration (BiOi, CiOi, VO, I) with dose is observed. And one unexpected larger peak appeared at the temperature range 80~130 K for 200 Mrad irradiated diodes. The above results were compared with data from TSC and Deep-Level Transient (DLTS) spectroscopy measurements achieved by the team of the CERN-RD50 “Acceptor removal project”.

Speaker: Mr Chuan Liao (Hamburg University (DE))

RD50_21-06-2022.pdf

11:20 Defect characterization studies on gamma-irradiated p-type Si diodes

Boron-doped silicon devices used in high radiation environment like the HL-LHC show a degradation in device performance due to the radiation induced deactivation of the active boron dopant. This effect is known as the so-called Acceptor Removal Effect and depends on particle type, energy and radiation dose. Here we present defect characterization studies using TSC (thermally stimulated current technique) and DLTS (Deep Level Transient Spectroscopy) to correlate radiation induced changes in the macroscopic device properties with the formation of microscopic defects. The defect spectroscopy techniques provide us information about defect characteristics such as activation energy, capture cross section and defect concentrations, and were performed on 60Co gamma-irradiated B-doped silicon EPI-diodes of different resistivity.

Speaker: Anja Himmerlich (CERN)

2022-06-21_RD50_talk_Himmerlich_gamma-irrad_measurements_v4_final.pdf

11:40 On the bistability of the Boron related donor associated with the acceptor removal process in irradiated p-type silicon

Silicon based sensors suffer from a phenomenon called “Acceptor removal” when exposed to high fluences of radiation. This “acceptor removal” process implies the elimination of the dopant element from the substitutional place (e.g., boron for p-type silicon) and combining with a different particle, obtaining an electrical active defect complex (in the case of boron-doped p-type silicon, obtaining an acceptor level from the new defect). This change of doping affects the macroscopic electrical properties and performances of the devices.
It was found previously observed that an irradiation induced defect containing Boron and acting as a donor (assumed to be the BiOi complex) is bistable, impacting thus on the determined acceptor removal rate in p-type silicon. The defect can exist in at least two configurations, labelled as A and B in the following. The present work focus on studying the conditions the defect can change its configuration. CV measurements after different excitation conditions of the samples, at different temperatures allow us to determine the frequency factors and activation energies required for the defect to change the configuration from A to B and back.

Speaker: Andrei Nitescu (National Institute of Material Physics -NIMP)

40th RD50_Andrei Nitescu.pdf

40th RD50_Andrei Nitescu.pptx

12:00 RD50 Project proposal: Defect engineering in PAD diodes mimicking the gain layer in LGADs

The proposed project is focusing on the acceptor removal process (ARP) in the irradiated gain layer of LGAD sensors, aiming to understand it and parametrize it for various content of B, C and O impurities and irradiation fluences, in order to find proper defect engineering solutions to maximize the radiation hardness of the gain layers. The studies performed so far on LGAds show that in the p+ layer of LGADs, the ARP can result in a complete disappearance of the gain at 1MeV neutron equivalent fluences higher than 2x1015 cm-2. As major obstacles preventing the achievement of enough knowledge for characterizing and proposing feasible solutions for improving the performance of the gain layers in LGADS are:
(i) the impossibility of performing the needed investigations after high irradiation fluences in the gain layer only, and determine the defects depth profile caused by B and C implantations in the p+ gain layer. This can be usually performed with DLTS when the applied voltage falls entirely only on the gain layer. However, in structures like LGAD, with Boron doped layers of different resistivity, the highly doped gain layer and the low doped bulk, DLTS cannot be applied. The only applicable method in LGAD structures is TSC which can evidence only overall signals generated by all the layers in LGAD devices, including possible also the contribution from the highly B-doped back contact, making the gain layer’ ARP characterization not reliable. In addition, by TSC one cannot follow a depth profile of the defects containing implanted impurities. Therefore, a reliable, comprehensive characterization of the gain layer after large fluences cannot be performed on LGAD structures. To characterize the ARP in the gain layer of LGADs one needs special samples containing only the gain layer. Such samples are to be produced via the present common project within RD50.
(ii) the bistability of a B-containing defect with a donor level at about 0.27 eV from conduction band of Silicon (generally attributed to the BiOi complex), measurable in only one of the two configurations – the BiOiA(0/+). This leads to an underestimation of the defect generation rate, gBiOi, and to a discrepancy with the Boron removal rate, gB, as estimated from CV/IV characteristics and used further for modelling the ARP. In addition, there are long time variations of both gBiOi and gB once the samples are exposed even shortly to the ambient light when manipulate them prior to start of the measurements.
For an undoubtful characterization of the ARP process in the gain layer of the LGADs and understand the gain loss in such structures, special samples, mimicking the gain layer in the presence of different amounts of B, O and C impurities, has to be fabricated and studied. CZ and FZ silicon wafers are preferred to start with because the B and O impurities are homogeneously distributed in the bulk of the samples. The variation of C content will be achieved by implantation.

Speaker: Ioana Pintilie

Ioana Pintilie-project gain layer.pdf

Ioana Pintilie-project gain layer.pptx

12:20 Discussion: Defects and Material Characterization

Speakers: Ioana Pintilie, Michael Moll (CERN)

Ioana Pintilie-40th_RD50-Defect_Discussion.pdf

Ioana Pintilie-40th_RD50-Defect_Discussion.pptx

vs_CompLGAD_40thRD50.pdf

12:50 → 14:00 Lunch Break

14:00 → 14:40 Facilities

14:00 EURO-LABS

The Horizon Europe project EURO-LABS will provide Transnational Access to Research Infrastructures (RI) for users from the Nuclear and Particle Physics communities. It comprises three pillars: Nuclear Physics, HEP Accelerators and HEP Detectors.

HEP Detectors RI's should be of vital interest to RD50. The RI's are grouped into 3 tasks dealing with Detector Characterization, Test Beams and Irradiations. The slate of RI's matches that in the TA od AIDA/AIDA2020, with increased budget in terms of Access Units and a few new facilities added.

The project will start on September 1st with a duration of 4 years.

Speaker: Prof. Marko Mikuz (Jozef Stefan Institute (SI))

WP4-RD50.pdf

WP4-RD50.pptx

14:20 Particle beam profilers based on fluence dependent variations of carrier lifetime and scintillation intensity in Si and GaN materials

The particle beam profilers, based on fluence measurements performed by recording the changes of carrier lifetime in Si material and scintillation intensity of thin GaN layers, caused by radiation induced defects and emission centres, will be presented. The beams of penetrative (26 GeV/c) and stopped (1.6 MeV) protons will be discussed.

Speaker: Tomas Ceponis (nstitute of Photonics and Nanotechnology, Vilnius University)

RD50-CeponisT-Final.pdf

14:40 → 15:45 Open CB: ECFA roadmap implementation plans

14:40 The Detector Roadmap

Speakers: Dr Giulio Pellegrini (Centro Nacional de Microelectrónica (IMB-CNM-CSIC) (ES)), Pellegrini, cartiglia

TF3_RD50.pptx

14:55 Detector Roadmap implementation - ECFA proposal

Speaker: Philip Patrick Allport (University of Birmingham (UK))

ECFA_Detector_R&D_Roadmap_RD50.pdf

ECFA_Detector_R&D_Roadmap_RD50.pptx

15:45 → 16:15 Coffee Break

16:15 → 19:15 Collaboration Board

https://indico.cern.ch/event/1171235/ (protected)

Wednesday, 22 June

09:00 → 12:40 Wide Band Gap Materials

09:00 GaN/AlGaN high electron mobility transistor characteristics after 1016 neq/cm2 neutron irradiation

Gallium nitride (GaN) and its related hetero-structure alloy AlGaN are wide band gap semiconductors which offer radiation-hard alternatives to silicon, particularly as the focus in the HEP community shifts toward technologies capable of operating in extremely high radiation fields such as fast hadron fluence greater than 1017 neq/cm2. High-electron mobility transistors (HEMTs) fabricated in epitaxial barrier/channel layers of AlGaN/GaN take advantage of the two-dimensional electron gas (2DEG) that forms naturally at the hetero-interface, producing a high density (1013 e-/cm2), high mobility (2000 cm2/V-s) conductor with a sheet resistance of ~ 300 Ω/square. This enables RF amplifier designs that can operate up to 40 GHz with 10 dB gain for 150 nm gate length, and switch designs with slew rates (dV/dt) greater than 100 V/ns, which is superior to Si MOSFETs. GaN and related alloys also have a higher critical field and higher threshold displacement energy than silicon, which inherently makes them more radiation-hard than Si.

In this work, irradiation results from NRC’s standard AlGaN/GaN HEMT process are presented. Nine chips, each containing a pattern of four discrete HEMTs with different gate lengths (Lg = 500 nm, 1000 nm, 1500 nm, 2450 nm) and constant gate width (Wg = 80 µm) were fabricated in-house on a SiC substrate then diced. HEMT DC I-V characteristics were subsequently measured before and after neutron irradiation at 1016 neq/cm2. Pre-irradiation values of the output current density and drain leakage current density were ~ 1.0 A/mm and ~ 10-6 A/mm, respectively at room temperature, falling within the yield norms for the NRC GaN HEMT process and indicative of good quality devices. After 1016 neq/cm2 neutron irradiation, the threshold voltage between ON and OFF states remained stable from an IC-design point of view, shifting consistently by ~ +0.4V (-4.1V before, -3.7V after) for all gate lengths. The average drain output current density was reduced by 16% for all gate lengths except 500 nm which fell by 21%. Since Lg primarily determines RF characteristics (fmax > 40 GHz measured for Lg = 500 nm pre-irradiation), this implies that future IC designs such as TIAs would not need to trade-off Lg (hence fmax) for radiation resistance. The average OFF-state drain leakage current density also fell (i.e., improved) between 77% and 86% on average from the initial ~ 10-6 A/mm values, but in this case a negative linear dependence for all gate lengths was measured, suggesting that two different mechanisms are affecting output current and leakage current densities during neutron irradiation.

These irradiation results show the relative stability of standard NRC GaN HEMTs subjected to 1016 neq/cm2, and are promising for our upcoming next generation GaN HEMTs incorporating process improvements for high-temperature and high-dose operation. The results also validate the parallel phase of the project plan to fabricate Schottky diode test structures for DC and DLTS measurements using 2” GaN wafers epitaxially grown on bulk GaN substrates. In the last part of this presentation, our first experience with the new GaN on GaN material and the follow-up steps in preparation of Schottky diode fabrication will be given.

Speaker: Dr Jean-Paul Noel (National Research Council Canada)

J-P Noel et al, GaN-AlGaN high electron mobility transistor characteristics after 10^16 neq neutron irradiation, V5 final.pdf

09:20 Study of the spectrometric performance of SiC detectors at high temperature

In future nuclear fusion reactors, it will be essential to diagnose suprathermal ions escaping from the plasma. The escaping suprathermal ions imply a loss of energy that leads to plasma cooling, in addition to compromising the integrity of the reactor wall material [1]. For the future ITER (International Thermonuclear Experimental Reactor) project, it will be of crucial importance to detect the 3.5 MeV alpha particles resulting from the D-T reaction. Nowadays, Fast Ion Loss Detectors (FILD) based on scintillation materials are the most widely used in magnetic plasma confinement devices [2], but these diagnostic systems have limitations in accomplishing the specifications needed to perform this task due to the high radiation and temperature levels.
At this time, one of the best alternatives is to use semiconductor detectors. Silicon carbide is a broad bandgap material with high thermal conductivity (3.7 W/(cm-°C)), which makes it suitable for high temperature applications. In this work, the spectroscopic performance of a 4H-SiC Schottky diode, fabricated by the Institute of Microelectronics of Barcelona (IMB), for the detection of 3.5 MeV alpha particles in the temperature range from room temperature (RT) to 450 °C is studied. In addition, the measured spectra have allowed to obtain the average electron-hole pair creation energy as a function of temperature with higher precision than in other works that can be found in the literature.

[1] A. Fasoli et al., Chapter 5: Physics of energetic ions. Nuclear Fusion 47, S264 (2007).
[2] M. Rodríguez-Ramos, M.C. Jiménez-Ramos, M. García-Muñoz, J. García López, Temperature response of several scintillator materials to light ions. Nuclear Instruments and Methods B 403 (2017) 7-12.

Speaker: Dr Maria Del Carmen Jimenez Ramos (Universidad de Sevilla (ES))

40th_RD50workshop_MCJR_subir.pdf

40th_RD50workshop_MCJR_subir.pptx

09:40 Caracterization of neutron irradiated IMB-CNM SiC planar diodes with TPA-TCT

A radiation tolerance study of planar diodes fabricated on a SiC substrate will be presented. TPA-TCT was used to characterize the samples. The measurement campaign was carried out at the laser facility of the EHU-UPV university.

Speaker: Cristian Quintana San Emeterio (Universidad de Cantabria and CSIC (ES))

2022-06-21_RD50-v3.odp

2022-06-21_RD50-v3.pdf

10:00 Impact of annealing on Ti/4H-SiC Schottky barrier diode radiation detector performance for fusion alpha-particle diagnostics.

Advanced fusion alpha-particle diagnostics in high D-T plasmas under high-fluences require efficient wide bandgap semiconductor detectors fabricated on 4H-SiC and Diamond materials. However, acquiring high-pure single crystalline diamond is difficult to fabricate large area detectors. This motivated to explore wide bandgap semiconductor 4H-SiC possessing high thermal conductivity suitable for harsh environments. This work includes electrical and spectral measurements of (Ti/Au)/4H-SiC Schottky barrier diode detectors when exposed to a Americium 241 alpha-source. Annealing procedure at 400 degrees centigrade for 5 minutes in nitrogen ambient was involved for few samples to observe the impact of annealing on spectral characteristics. Detector performance was quantitatively measured by determining parameters of energy resolution and charge collection efficiency. Improved alpha spectral characteristics upon annealing is attributed to the reduction of surface states at the interface which were plotted using forward current-voltage characteristics in this work. Detectors resolving the peaks in spectral characteristics highly depends on reverse leakage current of detectors which significantly reduced upon annealing is explained by finding out possible current conduction mechanisms.

Speaker: Mrs Shilpa Aluru (Indian Institute of Technology Tirupati)

10:20 Coffee break

10:50 Measurements and Simulations of High Rate 4H-SiC Particle Detectors

Compared to Silicon (Si), silicon carbide (SiC) has multiple advantageous material properties, making it an interesting candidate for high beam rate detectors. SiC features a higher charge carrier saturation velocity and breakdown voltage than Si, which allows for a high time resolution and aids in mitigating pile-ups. The large band gap of SiC improves its radiation hardness, which, together with its good thermal conductivity, limits the dark current even for very high beam rates and irradiation levels.

This talk presents measurements and simulations for a $50 \mu m$ thick 4H-SiC pad sensor. We show laboratory measurements using $\alpha$$/$$\beta$ sources, as well as multiple studies performed using high energy (up to 252.7 MeV) and high rate (several 100 MHz) proton beams. In order to investigate the effects of radiation-induced damage in SiC sensors, we present UV-TCT and proton beam measurements of neutron-irradiated samples with equivalent fluxes of up to $1\times 10^{16}$ $n/cm^2$ according to the NIEL hypothesis.

To guide future measurements and the construction of SiC low gain avalanche detectors (LGADs), we aim at using Monte Carlo simulations leveraging the AllPix$^2$ framework together with electric fields simulated by TCAD and COMSOL. We present our simulation workflow for AllPix$^2$ and show preliminary comparisons between measured and simulated data. Finally, current challenges specific to simulations of SiC (and SiC LGADs) are highlighted.

Speaker: Andreas Gsponer (Austrian Academy of Sciences (AT))

RD50_Talk_Andreas_Gsponer_HEPHY.pdf

11:10 Development of 4H-SiC Low Gain Avalanche Diode

Inspired by the Low Gain Avalanche Diode (LGAD) of Silicon, we investigate the possibilities to produce similar device using 4H-SiC, benefiting from the intrinsic characteristics of the wide band gap properties of Silicon Carbide, such as higher saturated carrier velocity, higher atom displacement energy as well as the recent technological improvement of high-quality epitaxy with high resistance from industry. Two prototypes of 4H-SiC LGAD devices with different design by Nanjing University (NJU) are introduced. The leakage current, capacitance, doping level and electric field of 4H-SiC LGAD are discussed by measurement and simulation.

Speaker: Tao Yang (Chinese Academy of Sciences (CN))

yangtao_40th_rd50_workshop_20220622.pdf

11:30 SiC Neutron Irradiaion Study at CSNS

The irradiation effect of Schottky 4H-SiC detector has been studied at the Back-n white neutron beamline at China Spallation Neutron Source (CSNS). The total irradiation flux of the white neutron with an energy peak of 1 MeV, is about 1e14n/cm2.Before and after irradiation, the alpha particle energy spectrums are compared, and the influence of neutron irradiation on the polarization effect of the detector is noticed through a long-term energy spectrum measurement.

Speaker: Rui Fan (Institute of High Energy Physics, CAS)

20220622SiC Neutron Irradiation Study at CSNS.pdf

11:50 Deveopment of 3D SiC radiation detector

A prototype of 360 um thick single crystal SiC has been fabricated with holes of 100um using laser drilling method. Form scanning electron microscope (SEM) images, there is no crack extending to the single crystal, and no residue on the side wall. It is found that the SiC sidewall is carbon-riched after laser and chemical treatment. The electrodes of 3D 4H-SiC device are formed by extruding the molten indium metal. The ohmic contact characteristic is formed. When 100 V voltage is applied, the current value are 6 pA and 10 nA under dark and 405 nm illumination conditions.

Speaker: Prof. Hongwei Liang (Dalian University of Technology)

Deveopment of 3D SiC radiation detector.pdf

12:10 Discussion: Wide Band Gap Materials

Speakers: Dr Giulio Pellegrini (Centro Nacional de Microelectrónica (IMB-CNM-CSIC) (ES)), Giulio Pellegrini (Universidad de Valencia (ES))

Rd50_milestones_new_structures.pdf

Rd50_milestones_new_structures.pptx

12:40 → 14:10 Lunch Break

14:10 → 17:35 IRRAD

14:10 Update on the ATLAS ITk Silicon Strip Sensors - Pre-production

The ATLAS upgrade for HL-LHC includes the installation of an entirely new all-silicon Inner Tracker (ITk). The part of the tracker further away from the IP is instrumented with silicon micro-strip sensors comprising 165m2 of active area in a nearly hermetic way. Multiple sensor shapes are utilized: square sensors in the barrel part and a stereo-annulus sensor design with curved edges to provide continuous coverage of the disc surface in the endcap part of a detector. As a result, there are 8 different strip sensor types in the system. They all feature AC-coupled n+-in-p strips with polysilicon biasing, developed to withstand a total fluence of 1.61015 neq/cm2 and a total ionizing dose of 66 Mrad. Following many years of R&D and 4 prototype submissions and evaluations, in 2020 the project transitioned into pre-production, where 5% of the total volume was produced in all 8 designs. In this contribution, we will summarize the evaluation program, test results, and experience with the pre-production sensors.

Speaker: Thomas Koffas (Carleton University (CA))

RD50_ITk_Strip_Sensor_QC.pdf

RD50_ITk_Strip_Sensor_QC.pptx

14:30 Study of depth-dependent charge collection profiles in irradiated pad diodes

In this work, charge collection profiles of non-irradiated and irradiated $150 \; \mu \text{m}$ $p$-type pad diodes were measured using a $5.2 \; \text{GeV}$ electron beam traversing the diode parallel to the readout electrode. Four diodes were irradiated to $1 \; \text{MeV}$ neutron equivalent fluences of 2, 4, 8, and $12 \times 10^{16} \; \text{cm}^{-2}$ with $23 \; \text{MeV}$ protons. By unfolding the measured charge collection profiles, the Charge Collection Efficiency profiles are extracted as a function of depth. The results of the measurements are compared to the simulation using three radiation damage models from literature which were tuned to different irradiation types and fluences.

Speaker: Mohammadtaghi Hajheidari (Hamburg University (DE))

RD50_Sildes.pdf

14:50 Surface and bulk properties of silicon sensors obtained from quality control test structures for the CMS experiment

In the following years, the LHC is going to be upgraded to the so called High Luminosity LHC (HL-LHC). Therefore, the CMS (Compact Muon Solenoid) detector will be adapted to the new conditions by incorporating new silicon sensors into the tracker and the calorimeter endcap. The strategy to monitor the quality and stability of the sensor production process is based on a test structure set, implemented at least twice on each production wafer, that provides access to critical process parameters. Process quality control parameters obtained from Metal-Oxide-Semiconductor Capacitors (MOS-C), Metal-Oxide-Semiconductor Field-Effect Transistors (MOS-FET), Diodes and other test structures are discussed. Additionally, first measurements of test structures irradiated with neutrons to study the impact of irradiation on surface and bulk properties are presented.

Speaker: Veronika Kraus (Austrian Academy of Sciences (AT))

2022_06_22_PQC_RD50_Talk_VK.pdf

15:10 Advanced approach for parameterization of the current generation centers in irradiated silicon sensors

An effective approach for evaluating the scenario of Si sensor radiation degradation requires parametrization of the bulk current generation and the electric field transformation in the irradiated sensors. The presented data show that the I-V characteristics of Si sensors damaged by short-range particles allow a reliable differentiating between these processes and defining the parameters of the effective radiation defects including their type and microscopic parameters, which control independently the generated current and the electric field.

Speaker: Ms Daria Mitina (Ioffe Institute (RU))

15:30 Announcement: Special Journal Issue on "Radiation Sensors and Detectors"

Dear Colleagues,

Radiation sensors and detectors are widely used in fundamental physics, nuclear reactors, aerospace science, medicine, environmental monitoring, etc. One of the most important aspects of these application areas is the extremely harsh radiation environment, driven by the next-generation fusion energy reactors and future high-energy particle detectors. It is crucial to develop radiation-resistant, easy-to-operate, high-spatial/temporal-resolution devices that can survive in environments with high radiation fluences and high temperatures, as expected in plasma diagnostics and high-energy particle collisions. Solid-state sensors, especially wide-bandgap semiconductors, are good candidates for these applications.

This Special Issue is addressed to all types of solid-state sensors designed for extremely harsh environments.

Dr. Xin Shi
Dr. Michael Moll
Guest Editors

Speakers: Michael Moll (CERN), Xin Shi (Chinese Academy of Sciences (CN))

Flyer--RSDMPA.pdf

Link to Website of Special Issue

Special-Issue-Sensors-Journal.pdf

15:35 Coffee break

16:00 Charge carrier mobility investigation in p-type Si after 6MeV electron irradiation

1 Vilnius University (LT)
2 Byelorussian State University (BY)

Corresponding author : algirdas.mekys@ff.vu.lt

Abstract: The radiation induced defects in silicon changes charge carrier transport properties, which are investigated by Hall and magnetoresistivity measurement techniques. The study concentrates on p-type Si material showing recent interest in BiOi defect formation. The irradiation of 6MeV energy electron fluence covers range from 1E+16 to 5E+16 /cm2. The analysis enables to extract free carrier thermal activation energy, the density of impurities and relate them to the irradiation fluence. The results are supplemented with the ones from thermal annealing.

Speaker: Dr Algirdas Mekys1 (Vilnius University)

Charge_carrier_mobility_p-type_Si_Mekys_RD50_2022_v2.pdf

16:20 Influence of radiation damage on the absorption of near-infrared light in silicon

To study the charge collection efficiency of radiation-damaged silicon
sensors, frequently red and near-infrared light is used to generate
electron-hole pairs . In order to determine the absolute number of
produced charge carriers, the light absorption coefficient, $\alpha$,
has to be known.

To study the change of $\alpha$ due to radiation-induced defects, we
have measured the transmission of light with wavelengths between
1-2\,$\mu$m through silicon samples irradiated to
1$~$MeV-neutron-equivalent fluences between 0 and $1 \times 10^{17}~$cm$^{-2}$.

In this contribution, the results of these measurements will be
presented: the contribution of the irradiation to $\alpha$ was found to
scale with fluence for the entire fluence range investigated. In the
wavelength region around 1.8\,$\mu$m, evidence for the production of the
radiation-induced divacancy defect $V_{2i}^0$ with a density
approximately proportional to the fluence was found. For the band-gap
energy, no fluence dependence was found within the experimental
uncertainties.

Speaker: Annika Vauth (Universität Hamburg)

2022-06-22_rd50.pdf

16:40 Polymer Based Ionizing Radiation Detectors

Recently, semiconductive polymeric materials have attracted attention as an active layer for the detection of ionizing radiation because of their excellent properties such as flexibility, easy production, solution processability and low-cost production. This paper presents X-ray detection properties of Poly(3-hexylthiophene) (P3HT) : Phenyl C61 butyric acid methyl ester (PCBM) blend structure with different PCBM loading ratios. P3HT:PCBM active layer based X Ray detectors were fabricated and effect of PCBM ratio was investigated. All devices were constructed bulk resistive type with ohmic contacts. Spray coated graphite electrode was used as top ohmic contact for all devices. P3HT:PCBM ratio was chanced as (1:0), (1:0.5), (1:1), (1:2) and investigate PCBM concentrations how effect X Ray detection parameters with different X Ray dose rate under 10 V bias. Photocurrent of the pure P3HT (1:0) based device increase under X Ray exposure but never reached to steady state level. However, when PCBM loaded into the P3HT photocurrent reached steady state current for all PCBM concentrations. X ray dose rates were changed form 0.35 mGy.s-1 to 8.74 mGy.s-1 for all devices. The photocurrent versus time graph characteristic for PCBM loaded P3HT based devices was saw-tooth shaped. The saw-tooth structure of the photocurrent by applying different dose X-Ray can be indicating potential usage for the X-ray detection.

Speaker: Sadullah Ozturk (Istanbul University-Cerrahpasa (TR))

Polymer Based Radiation Dedectors.pdf

Polymer Based Radiation Dedectors.pptx

17:00 Discussion: IRRAD

Speaker: Prof. Marko Mikuz (Jozef Stefan Institute (SI))

Extreme-TF3-Apr21.pdf

Thursday, 23 June

09:00 → 12:10 Low Gain Avalanche Detectors

09:00 High-Precision Tracking with Large Pixels using Thin Resistive Silicon Detectors

The implementation of resistive read-out in the design of silicon sensors places built-in charge sharing among neighboring pixels as the basic principle of operation. Resistive Silicon Detectors (RSD), exploiting the signals seen on the electrodes surrounding the impact point, achieve micron-level position resolution even with very large pixels. In this paper, results obtained with sensors from the second RSD production at the Fondazione Bruno Kessler are presented. A position resolution better than 3% of the pixel size is obtained for pitch ranging from 200 to 1300 μm.

Speaker: Nicolo Cartiglia (INFN Torino (IT))

Cartiglia_RD50_final.pdf

Cartiglia_RD50_final.pptx

09:20 TCAD simulation of impact ionization in non-irradiated LGADs

We present TCAD simulations of non-irradiated LGAD sensors (HPK and CNM). CV curves are used in combination with SIMS/SRP/TPA-TCT measurements to determine the doping profiles and with them the electric field within the LGAD bulk and gain layers.

Various impact ionization models available within the Synopsys TCAD framework, as well as the Masetti model are evaluated and finally a fit to experimental gain measurements (TCT) is performed to extract model parameters that can be used for further studies. In this presentation we concentration on the concept of fitting. In the second presentation (see E.Curras talk) we focus on Temperature dependence of the impact ionization parameters.

Speaker: Michael Moll (CERN)

220622-TCAD-LGAD-gain_mm_vs2.pdf

220622-TCAD-LGAD-gain_mm_vs2.pptx

09:40 New impact ionization parameters

In order to understand better the performance of LGADs, in particular in terms of Gain and breakdown voltage, it is important to know with high precision the structure of the devices and have a very accurate impact ionization model. There are several impact ionization models in the literature and many studies have been done in this respect, but no one is able to fit the empirical data taken in the lab with LGADs. Combining simulation and measurements, we extracted more accurate impact ionization parameters: alpha and beta as a function of the electric field and temperature. The work is presented in this talk.

Speaker: Esteban Curras Rivera (CERN)

RD50_CERN_JUN_2022_ECurras.pdf

10:00 Effect of Carbon co-implantation on radiation hardness of IHEP_IMEv2 LGAD

The radiation hardness of LGAD depends on the distribution and doping concentration of implanted Carbon and Boron. Based on Secondary Ion Mass Spectrometry profile of IHEP_IMEv2 LGAD devices, the impact of implantation dose and thermal load of Carbon to the radiation hardness of LGAD is discussed. A model based on the SIMS data is implemented to fit the accepter removal coefficient of LGADs and extrapolated to PIN structures. Its validity will soon be examined by the next version of IHEP LGAD.

Speaker: Yuan Feng (Chinese Academy of Sciences (CN))

RD50_40th_YuanFeng.pdf

10:20 Coffee break

10:50 Measurements on last IMB-CNM LGADs production

Abstract: In this contribution we will present the first measurements on LGADs corresponding to our CNM’s second engineering run based on 6-inch, 50µm active layer thick, epitaxial wafers (6LG3 technology). Some of the wafers were carbon enriched using two different doses and one implantation energy. For the gain layer, samples were fabricated using different boron doses and diffusion times and one implantation energy. Measurements, simulations and analysis of breakdown and depletion voltages were carried out on these LGADs. The presented results will serve as a stepping stone to select the best technological parameters for the gain and carbon layer definition in the upcoming ATLAS-CMS common run, based on 6-inch Si-Si wafers (6LG2 technology).

Speaker: Mr Jairo Antonio Villegas Dominguez (IMB-CNM (CSIC))

Measurements on last IMB-CNM LGADs production - 40thRD50 - Jairo Villegas.pdf

11:10 High temperature annealing of irradiated LGADs

LGADs irradiated up to 6e15 n/cm2 with reactor neutrons were annealed at high temperatures between 300C and 450C. Annealing was for 30 minutes in steps of 50C. CV measurements were made after each annealing step and a significant increase of gain layer depletion voltage was observed. Charge collection and timing resolution were measured with electrons from Sr-90 showing beneficial effect of short term high temperature annealing of irradiated LGADs.

Speaker: Gregor Kramberger (Jozef Stefan Institute (SI))

GK-LGAD-HT-Annealing.pdf

11:30 Recent results of the carbonated USTC-IME LGADs and fabrication of the AC-LGADs at USTC NRFC

The Low-Gain Avalanche Detector (LGAD) with timing resolution better than 35(70) ps before (after) irradiation is the key technology that has been studied by many RD50 institutes and is going to be used in the ATLAS HGTD upgrade. The University of Science and Technology of China (USTC) has been developing LGAD sensors with the Institute of Microelectronics of the Chinese Academy of Sciences (IME) and the Nano Research and Fabrication Center (NRFC) of USTC. The prototypes of DC and AC coupled LGADs have been produced. The recent development focused on carbon diffusion and large array fabrication. The prototypes have been tested by serval methods including IV/CV, beta-scope, laser-TCT as well as the electron/hadron beam test. The irradiation hardness is tested with the samples irradiated by reactor neutrons at the JSI. The c-factors are extracted and compared. The uniformity is characterized both by the on-wafer test and 5x5/15x15 array probe-card test. The latest results have shown that the prototypes can provide enough charge (>4fC) and good timing resolution(<70ps) after 2.5E15 neq/cm^2 and meet the specification of the HGTD upgrade. The novel structure LGADs fabricated by the NRFC LGADs show good performance with a yield at an acceptable level.

Speaker: Xiao Yang (University of Science and Technology of China (CN))

XYang_40th_RD50_220622.pdf

11:50 Before and after irradiation performance of IHEP-IME LGAD sensors

The High Granularity Timing Detector (HGTD) project of ATLAS will reduce the pile-up effect in HL-LHC by providing precise time measurement of tracks. The Low Gain Avalanche Detector (LGAD) with a time resolution better than 35(70) ps before(after) irradiation is the key technology that has been studied by many institutes. The Institute of High Energy Physics Chinese Academy of Science (IHEP) has been developing LGAD sensors IHEP-IME with the Institute of Microelectronics of the Chinese Academy of Sciences (IME). So far two versions of IHEP-IME LGAD sensors have been produced, IHEP-IMEv1 and IHEP-IMEv2. IHEP-IMEv1 sensors showed good potential in achieving the HGTD requirements. IHEP-IMEv2 sensors have a modified doping profile compared with the last version, especially focusing on the carbon implantation effect. Sensors with diverse producing processes and carbon doses were fabricated and have shown improved performance. What’s more, full-size sensors (with 15x15 pads) were produced. Sensors were irradiated with neutron influences of 0.8e15 neq/cm2, 1.5e15 neq/cm2, and 2.5e15 neq/cm2. This talk will present the test results of IHEP-IMEv2 sensors performance before and after irradiation, including single pad and large array sensors. After irradiation, sensors with different carbon doses showed different performances. The effect of carbon implantation will be shown. Low-temperature beta test results showed that after 2.5e15 neq/cm2 irradiation sensors collect 4 fC at less than 400 V with a time resolution better than 50 ps, by far satisfying the requirements.

Speaker: Xuewei Jia (Chinese Academy of Sciences (CN))

40th_RD50_Xuewei_220623_IHEP_IME.pdf

12:10 → 13:40 Lunch Break

13:40 → 17:00 Low Gain Avalanche Detectors

13:40 Review of our understanding on the limits of LGAD as studied by the low energy ions, low energy protons and femtosecond laser beams: Past, present and future experiments

In this presentation I will overview our accumulated knowledge about limits of LGAD as studied using the low energy ions, low energy protons and femtosecond laser beams. A new insight into old data will be given as well. A proposal for a new experiment that will explore 30 MeV proton beams at the Cyclotron in Prague will be announced as well as the the future plans at RBI through Radiate user scheme.

Speaker: Gordana Lastovicka Medin (University of Montenegro (ME))

SEB_GainSupression_Overview_GordanaMedin.pdf

14:00 The interpad distance study in Trench Isolated LGAD (TI-LGAD) using Femtosecond laser based SPA and TPA

In this presentation we will present the preliminary results from the interpad study in TI-LGADs using Femtosecond laser based SPA and TPA. The selected samples are from the latest FBK TI-LGAD production (RD50 project). To our best knowledge, the femtosecond laser based SPA and TPA has not been yet tested and tuned for the IP studies. .

Speaker: Gordana Lastovicka Medin (University of Montenegro (ME))

TI-LGAD_IP_study_GordanaMedin.pdf

14:20 The gain reduction mechanism in Low Gain Avalanche Detectors investigated with the TPA-TCT

The Two Photon Absorption – Transient Current Technique (TPA-TCT) setup at CERN uses fs pulse infrared fiber lasers, with a wavelength of 1550nm. Highly focusing optics are used to mainly generate excess charge carriers in a small volume (approximately 1µm × 1µm × 20µm) around the focal point of the laser beam, which enables a resolution in all three spatial directions. The setup was used to study plasma effects in a PIN sensor, and the gain reduction mechanism in a 300µm thick LGAD sensor. Furthermore, the impact of diffusion on the gain reduction mechanism was modeled and employed towards the data.

Speaker: Sebastian Pape (Technische Universitaet Dortmund (DE))

2021_06_23_40thRD50_pape.pdf

14:40 Observation and characterisation of the charge screening effect in LGAD

The recently observed saturation of the charge multiplication mechanism in LGAD devices has been studied and characterised with an infrared laser used to replicate the particle charge deposition ranging from 1 to 80 equivalent MIPs. The observations are compared to the response from beta particles and impinging protons with different energies. The influence of regions with high electric field values, above 10 V/$\mu$m, on the saturation of the gain mechanism, has been studied via 2D and 3D Technology CAD device simulation.

Speaker: Valentina Sola (Universita e INFN Torino (IT))

vs-Qscreening-40thRD50.pdf

15:00 Guard-ring design optimization in thin UFSD

In this contribution, the performances of several different guard-ring designs implemented in thin UFSD are compared. The sensors used in the analysis are part of the UFSD 4 production of the Fondazione Bruno Kessler.
The designs include different edge widths, numbers and layouts of floating guard-ring. The results include the measurement of noise and break-down voltage before and after irradiation.

Speaker: Marco Ferrero (Universita e INFN Torino (IT))

MF_230622_RD50.pdf

15:20 Coffee break

15:50 Geometry optimization of AC-coupled LGADs for high precision 4D tracking

Low Gain Avalanche Detectors (LGADs) are thin silicon detectors capable of providing measurements of minimum-ionizing particles with time resolution as good as 17 ps. These properties make LGADs the prime candidate technology for achieving 4D tracking in future experiments. Furthermore the fast rise time and short full charge collection time (as low as 1 ns) of LGADs are suitable for high repetition rate measurements in photon science and other fields. Granularity in traditional DC-LGADs is limited to the mm scale due to protection structures preventing breakdown caused by high electric fields at the edge of the segmented implants. The structure, called Junction Termination Extension (JTE), causes a region of 50-100 μm of inactive space in between electrodes.
In this contribution, a set of measurements on AC-coupled LGADs (AC-LGADs, also named Resistive Silicon Detectors, RSD) will be presented. AC-LGADs overcome the granularity limitation of traditional LGADs and have been shown to provide spatial resolution of the order of 10s of μm. This remarkable feature is achieved with an un-segmented (p-type) gain layer and a resistive (n-type) N-layer. An insulating di-electric layer separates the metal readout pads from the N+ resistive layer. Because of the AC-coupled nature of AC-LGADs the pulse is bipolar with a theoretical zero area. The high spatial precision is achieved by using the information from multiple metal pads, exploiting the intrinsic charge sharing capabilities of the AC-LGAD provided by the common resistive N-layer. The following detector parameters have been investigated: sheet resistance (resistivity of the N+ layer), oxide thickness, doping profile of the gain layer, pitch, size and shape of the readout metal pads. The response of non-conventional metal structures in AC-LGADs such as crosses and microstrips was also evaluated. AC-LGADs fabricated at the Fondazione Bruno Kessler (FBK) and at Brookhaven National Laboratories (BNL) were studied extensively with a focused IR-Laser and the result of the studies will be reported in this contribution. Sensors were mounted on fast analog electronic boards (with 1 GHz of bandwidth) and digitized by a fast oscilloscope. Sensors mounted on boards are measured in a laser TCT system using an infrared (IR) 1064 nm laser with a penetration length in silicon of several mm. The IR laser produces linear ionization across its path mimicking the behavior of a minimum ionizing particle (MIP). The laser beam is focused by a lens system that can produce a laser spot of 20-30 μm. The board is placed on micrometer motorized stages to allow to study the response of the sensor as a function of laser position.

Speaker: Dr Simone Michele Mazza (University of California,Santa Cruz (US))

160622_AC_LGAD_geometries.pdf

16:10 Timing Resolution Comparison between LGADs and 3D Sensors

Current and future collider experiments are reaching luminosities at which pile-up causes tracking of single particles to become near impossible when using only three spatial coordinates. However, with high enough timing resolution, an additional measurement coordinate could be introduced to unambiguously discern particle paths.

When it comes to ultra fast silicon detectors (UFSD), Low Gain Avalanche Diodes (LGADs) are currently a premier choice, reaching a time resolution of below 30$\,$ps. However, due to the limited radiation hardness (up to ${\sim2\cdot10^{15}\,\mathrm{n}_{\mathrm{eq}}/\mathrm{cm}^{2}}$) of the gain layer, LGADs, in their current form, do not seem viable for future colliders such as the FCC, where fluences up to ${10^{17}\,\mathrm{n}_{\mathrm{eq}}/\mathrm{cm}^{2}}$ are expected.

An alternative approach for UFSD are 3D detectors due to their superior radiation hardness as well as high granularity allowing them to be used to resolve particle tracks precisely in four dimensions. In this talk, timing measurements conducted at the University of Freiburg with both a TCT and a Sr-90 source setup of LGADs and 3Ds are compared pre and post irradiation with reactor neutrons.

Speaker: Montague King (Albert Ludwigs Universitaet Freiburg (DE))

RD50MontagueKing.pdf

RD50MontagueKing.pptx

16:30 Discussion: LGADs

Speakers: Gregor Kramberger (Jozef Stefan Institute (SI)), Nicolo Cartiglia (INFN Torino (IT)), Dr Salvador Hidalgo (Instituto de Microelectronica de Barcelona (IMB-CNM-CSIC))

GK-LGAD-Discussion.pdf

GK-LGAD-Discussion.pptx

17:00 → 18:25 New Structures

17:00 Power dissipation and hit efficiency of CNM 3D pixel sensors irradiated to 1.6e16 neq/cm$^2$

The Large Hadron Collider (LHC) will be improved to be able to reach about seven times its current nominal instantaneous luminosity. The High-Luminosity LHC (HL-LHC), is planned to start operation in 2027. To face the consequent increase of the particle fluence close to the proton-proton interaction point, the ATLAS detector will include in its upgraded Inner Tracker (ITk) new sensor technologies. In particular, 3D pixel sensors have been chosen for the inner most pixel layer of ITk because of their high-radiation tolerance.

Novel 3D pixel sensors were manufactured at CNM using a single-side technology on Silicon on Insulator (SOI) wafers. The active thickness for those pixel sensors is 150 µm. Two kinds of pixel sensor were manufactured featuring cells of 50 x 50 µm$^2$ and 25 × 100 µm$^2$ both with one collecting electrode. In the ATLAS ITk the 50x50 µm$^2$ pixel sensors will be mounted in the rings of the innermost layer, while the 25x100 µm$^2$ will be loaded in the barrels. CNM sensors were connected to a RD53A chip prototype and irradiated with proton beams in different facilities up to a neutron equivalent fluence of 1.6E16 neq/cm$^2$. The modules were then tested on an electron beam at DESY. In this presentation, I am going to show their power dissipation and their hit efficiency performance measured at two different incident angles, 0º (normal to the incident beam direction) and at 15º.

Speaker: Juan Ignacio Carlotto (IFAE - Barcelona (ES))

23062021_RD50_ workshop_Carlotto.pdf

17:20 Time resolution of single cell 3D devices on SPS pion beams

The proven potential of 3D pixel at higher than 10$^{16}$ n$_{eq}/cm^{2}$ radiation fluences, in combination with a small cell approach, makes them an ideal choice for a precision timing tracker. In this study, the timing resolution of several different geometry 3D pixel cells is presented using 160 GeV SPS pion beams. Through a varied incidence angle study, field uniformity, Landau contribution and collected charge are studied at incidence angles of $+/- 12^{o}$. Using state of the art numerical methods, the choice of instrumentation on signal composition and induced result bias is also evaluated. The study is expanded for four radiation fluences, up to $10^{17} n_{eq}/cm^{2}$ with the use of the EUDAQ telescope, providing sub-pixel timing maps with a 5$\mu$m spacial resolution.

Speaker: Dr Vagelis Gkougkousis (CERN)

RD50_Gkougkousis.pdf

17:40 Graphene-Enabled Silicon-Integrated Radiation Detector for Low Penetrating Particles

We present a novel scalable graphene-silicon hybrid photodiode that enables deep UV imaging. We have a created a photodiode with a reduced dead layer entrance window. Existing photodiodes are limited in sensitivity for low wavelengths due to the low penetration depth of photons of < 400 nm. Typical photodiodes have a junction implant which causes the low penetrating photons to be recombined in this dead layer. Here, we have utilized the near transparent nature of single layer graphene to create a junction with a minimum dead layer. To have a full active bulk volume we have combined a single junction ring (n++ bias ring) with single layer graphene. The graphene acts as a large field plate which overhangs the junction ring, on top of a thin dielectric, and covers the entire active area, 5x5 mm2. When a reverse bias is applied the detector depletes as one would expect the region underneath a field plate to deplete. Transient Current Technique (TCT) measurements have been performed to study the charge uniformity of the device and it has been shown that the charge collected is 100% across the entire area of the detector, however the collection time increases as you move further away from the junction ring this is due to the path length of the electrons along the surface of the device. Additional characterizations have been performed to evaluate the sensitivity of the device as a function of wavelength in comparison to a device with an ultra-shallow junction implant. The results show that the graphene-enhanced device shows far greater performance in the 200-400 nm wavelength range. It has been shown that this technology can be used to create a hybrid pixel detector for DUV imaging

Speaker: Giulio Pellegrini (Centro Nacional de Microelectrónica (IMB-CNM-CSIC) (ES))

Pellegrini_RD50.pdf

Pellegrini_RD50.pptx

18:00 Discussion: New structures

Speakers: Dr Giulio Pellegrini (Centro Nacional de Microelectrónica (IMB-CNM-CSIC) (ES)), Giulio Pellegrini (Universidad de Valencia (ES)), Gregor Kramberger (Jozef Stefan Institute (SI))

Rd50_milestones_new_structures - Copy.pdf

Rd50_milestones_new_structures - Copy.pptx

18:20 Workshop Dinner - Instructions

Speakers: Yana Gurimskaya (CERN), Yana Gurimskaya (Universite de Geneve (CH))

slide_RD50_dinner.pdf

Friday, 24 June

09:00 → 12:40 Monolithic devices

09:00 DMAPS activities of the PSI high energy physics group

The high energy physics group of PSI is involved in the CMS experiment. Since 2018 the group is also gaining experience in monolithic devices. This talk gives a summary of the group's DMAPS activities.

Speaker: Tilman Rohe (Paul Scherrer Institute (CH))

Rohe_RD50_24-06-2022.pdf

09:20 QFG transistors radiation damage effects

Highly integrated and very low power microelectronics, as required by Read Out Chips, represents a challenge because maximum performance and minimum power consumption are opposite design requirements. Quasi Floating Gate transistors are a solution because they allow independent control of transistor static and dynamic operation: AC and DC input terminals are different. The DC input terminal has a big equivalent resistor, implemented as a mos reverse biased diode. Radiation displacement damage in mosfet electronics is not tipically an issue because Total Ionization Dose (and Single Event) effects are more relevant due to the shallowness of the active structures in the devices. But body diodes used in the QFG transistors are sensitive to radiation damage. In this work we analyze from first principles the radiation damage sensitivity of QFG transistors, we present experimental results after irradiation with gamma rays and discuss consequences for microelectronic designs.

Speaker: Francisco Rogelio Palomo Pinto (Universidad de Sevilla (ES))

RD50_June2022_qfg_Final.pdf

RD50_June2022_qfg_Final.pptx

09:40 Stitched Passive CMOS Strip Sensors

As a result of a CERN market survey, CMOS sensors in pixel and strip geometries were developed. The CMOS process is an established commercial industry process, which a lot of foundries utilize to produce silicon type devices. Typical CMOS foundries are equipped for bulk productions, but only for sensors much smaller than what is needed in e.g. the strip region of the ATLAS Inner Tracker. To produce large enough sensors, the process of stitching is utilized. The sensor structure is divided up into different regions, which individual wafer masks can imprint side by side onto the wafer to form a coherent area. With this method, the sensors can be nearly wafer-sized. The effects of stitching on charge collection, electric field strength and configuration, detection efficiency and radiation hardness have to be investigated.

The sensors discussed in this talk are stitched passive CMOS strip sensors produced by LFoundry in a 150$\,$nm process with three different strip designs. The results of electrical IV characterisations, TCT and $^{90}$Sr-source measurements and the effects of radiation damages are discussed. The effects of the stitches on the sensors performance were also investigated.

The results of these measurements demonstrate that the stitching process works and introduces no negative effects on the sensors performance, before and after irradiation.

Speaker: Niels Sorgenfrei (Albert Ludwigs Universitaet Freiburg (DE))

Niels_Sorgenfrei_RD50_Talk.pdf

10:00 Timing properties of the RD50-MPW2 HVCMOS chip

The CERN-RD50 collaboration has been developing radiation hard High Voltage CMOS detector prototypes based on high resistivity substrate and large collection electrode, manufactured in LFoundry 150 nm process. In this contribution we will present measurements of timing properties of the RD50-MPW2 chip, which features an 8 x 8 matrix of active pixels with integrated analog front end and discriminator circuits that can be monitored by a fast oscilloscope.
Charge in the sensor was generated by short laser pulses and by beta electrons from Sr-90 source. In measurements with Sr-90, the timing response of the DUT was evaluated relative to a fast reference signal from an LGAD. Time walk and time resolution of the system were measured from the recorded waveforms and compared to detector response to charge injection with a pulse generator. Measurements were made with detectors before and after neutron irradiation.

Speaker: Jernej Debevc (Jozef Stefan Institute (SI))

RD50-MPW2_timing_measurements_Debevc_v3.pdf

10:20 Coffee break

10:50 RD50-MPW3: General details and pixel matrix

The CMOS Working Group of CERN-RD50 has designed and submitted RD50-MPW3, which is the third High Voltage CMOS (HV-CMOS) pixel chip developed by the collaboration to further study these sensors for future physics experiments. The design of RD50-MPW3 incorporates the lessons learnt from the previous two chips, RD50-MPW1 and RD50-MPW2. It inherits the structures for high breakdown voltage and low leakage current, the fast analog readout circuits and the well-performing bias block and analog buffer from its two predecessors.

RD50-MPW3 is a more advanced prototype with a matrix of 64 × 64 pixels which integrate both analogue and digital readout electronics inside the sensing diodes. To alleviate routing congestion and minimise crosstalk noise, the pixels are serially configured and organised in a double-column architecture. This prototype has optimised digital peripheral readout electronics for effective chip configuration, based on the I2C protocol with internal Wishbone bus, and fast data transmission.

This contribution gives an overview of the general details of RD50-MPW3 and focusses on the design aspects of the pixel matrix. The design of the digital periphery of the chip, and of the electronics beyond the chip, will be presented in a separate contribution to this workshop.

Speaker: Chenfan Zhang (University of Liverpool (GB))

RD50 40th workshop (CERN)_Chenfan.pdf

11:10 RD50-MPW3: Digital readout and DAQ developments

This contribution can be seen as a continuation of the talk “RD50-MPW3: General details and pixel matrix”. This presentation focuses on the digital periphery of the chip and how it is integrated to the DAQ system, thus it is discussing a distinct topic.
A brief overview of the digital periphery is followed by a more detailed introduction of the data acquisition concept and software. The main aspects of the digital periphery are presented and challenges during the design are discussed and links for further information are provided.
The readout framework is based on the Caribou system and details about firmware, software and integration into a test beam setup are given. This includes details about data-flow, configuration as well as synchronization with other detectors in a typical test beam environment.

As the chip has not been delivered yet, we cannot show detailed measurements. Nevertheless, preliminary tests to prove the functionality of our readout chain are shown. Finally, a short outlook including our plans for test beams and building our own telescope demonstrator are presented.

Speaker: Patrick Sieberer (Austrian Academy of Sciences (AT))

RD50WS_Juni_2022_Patrick_Sieberer.pdf

RD50WS_Juni_2022_Patrick_Sieberer.pptx

11:30 Data Readout for Advanced Designs (DRAD), an update

Particle detectors systems need state of the art Data Acquisition Systems as backend. DRAD (Data Readout for Advanced Designs) is a a new DAQ with a client-server data architecture able to handle up to 4 Hybrid Pixel Detectors simultaneusly. At the present, DRAD operates with the OC4SENS read-out chip but is easily adaptable to other pixel detectors. The DAQ is based on a System-on-Module (SoM) that includes FPGA logic fabric and microprocessors. The client-server architecture is enabled by a Linux operating system. The full DAQ is very compact, reducing the hardware load typically needed in particle tracking experiment, specifically during the compulsory particle telescope characterization.

Speaker: Francisco Rogelio Palomo Pinto (Universidad de Sevilla (ES))

RD50_June2022_drad.pdf

RD50_June2022_drad.pptx

11:50 Discussion: Monolithic Devices

Speaker: Eva Vilella Figueras (University of Liverpool (GB))

20220624_Vilella_RD50WS_CMOS_discussion.pdf

12:20 Goodbye

Speaker: Michael Moll (CERN)

220624-RD50-Goodbye_v0.pdf

220624-RD50-Goodbye_v0.pptx

12:40 → 14:10 Lunch Break