14th RD50 Workshop
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Europe/Zurich
Freiburg, Germany
Freiburg, Germany
Michael Moll
(CERN),
Ulrich Parzefall
Description
14th RD50 Workshop on Radiation hard semiconductor devices
for very high luminosity colliders
Participants
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13:30
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Welcome
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13:30
Welcome to the 14th RD50 Workshop 20mSpeakers: Mara Bruzzi (Dipartimento di Fisica), Michael Moll (CERN), Ulrich Parzefall (Uni Freiburg)
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13:30
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Pad Detector Characterization and Defect Engineering
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13:50
Capacitance Measurements and Depletion Voltage for Annealed Fz and MCz Diodes 20mWe irradiated n and p-type Float Zone (FZ) and magnetic Czochralski (MCz) silicon diodes with protons up to 1.4 x 10^15 neq/cm2. The devices were annealed at 60 °C and measured after 10, 80, 1,000 and 10,000 minutes. Capacitance and leakage current measurements were performed at room temperature and the depletion voltage extracted. A comparison of the different device types will be presented.Speaker: Jessica Metcalfe (Department of Physics and Astronomy-University of New Mexico-Unk)
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14:30
Electrical Characterization of Irradiated Silicon Diodes at Different Temperature 20mFor CV/IV characterization of irradiated silicon detectors a standard temperature of 20°C and frequency of 10 kHz are adopted. However, at high irradiation level it is necessary to perform measurements at lower temperature. The obtained values Vfd and Id depend on the temperature and frequency, as well as on material and radiation type and the fluence. To study this dependence CV/IV measurements in the temperature range from -10°C to 20°C and in the frequency range from 100 Hz to 100 kHz, as well as charge collection measurements were performed for epitaxial and MCz silicon diodes after irradiation with 24 GeV/c protons and reactor neutrons of different fluences.Speaker: Vladimir Khomenkov (Hamburg University)
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14:50
TCT-Measurements of mixed irradiated Magentic Czochralski Diodes in the SLHC-Scenario 20mMagnetic Czochralski Diodes both n-type and p-type of 300um thickness were irradiated with protons and neutrons to fluences corresponding to different Radii in the CMS-Tracker. IV- and CV-Measurements were performed to study the depletion behaviour of diodes with increasing current. Measurements with a TCT-Setup with red and infrared laser light are in progress to extract trapping times and charge collection efficiency.Speaker: Robert Eber (IEKP, UNI-Karlsruhe (TH))
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15:10
Charge collection and trapping effects in n-type and p-type epitaxial silicon diodes after proton irradiation 20mEpitaxial silicon pad diodes of p-type (150 µm, ST material) and n-type (75 µm, 100 µm, 150 µm, both ST and DO) material have been investigated after 24 GeV/c proton irradiation at CERN PS. Time-resolved TCT measurements with 670 nm laser light (front injection) were performed for 150 µm thick diodes and thus the effective trapping time constants for electrons (n-type) and holes (p-type) could be obtained. CCE measurements with 5.8 MeV alpha particles and 670 nm and 1060 nm laser light showed an anomalously high charge collection.Speaker: Joern Lange (Hamburg University)
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15:30
Coffee break 30m
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16:00
Determination of strip detector properties by using Edge-TCT 20mTransient Current Technique (TCT) was used to evaluate p-type silicon micro-strip detectors. A pulsed IR laser focused to a spot of to 6 μm illuminated the detector edge so that the beam was parallel with the surface and perpendicular to the strips. In that way electron hole pairs were created at known depth in the detector. Scans over the entire detector thickness with 0.5 μm resolution were performed. For each laser beam position the induced current shape is measured for one of the strips. The charge collection efficiency was studied as a function of laser position (depth of carrier generation), voltage, integration time. Determination of electric field profiles without relying on precise values of effective trapping times will be discussed.Speaker: Gregor Kramberger (Jozef Stefan Institute)
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16:20
New TCT setups at CERN and Louvain 20mNew strip sensitive TCT & CCE setups are under construction in colaboration between CERN and Louvain. Mechanics and electronics are realized in a twin solution in both test stations. Focused red laser beam will be used for standard and strip sensitive TCT. Sr 90 source and IR laser will be used for calibration and fast CCE. A fix optical fiber setup with splitters and shutters avoids maladjustement and thus allows reliable measurements with laser as well. Cooling is done with vacuum and silicon oil (CERN) and cold nitrogen vapour (Louvain). Usage of Alibava within the cooled setup is in preparation.Speaker: Manuel Fahrer (CERN)
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16:40
Predictions on charge collection efficiency in heavily irradiated Si detectors basing on the approach of active base region 20mThe approach of an active base with a non-zero electric field in heavily irradiated Si detectors is further developed for estimations of the collected charge up to the fluences of super-LHC range (10^16 cm^-2). The steady-state electric field in heavily irradiated detector has double peak shape with two maxima and the base region in between, in which the electric field is about few kV/cm. Using this approach, the collected charge vs. fluence dependence is calculated and compared to that in the detector with a standard linear electric field. The study is carried out for pad detectors and strip detectors typical for ATLAS topology. Fitting of the calculated charge collection efficiency vs. fluence dependence to the experimental curves allowed definition of the main base parameters. It is shown that the electric field in the active base depends on the irradiation fluence and stimulates an essential increase of the collected charge.Speaker: Elena Verbitskaya (Ioffe Physical Technical Inst.)
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17:00
Contributions of Electrons and Holes to Total Collected Charge in Heavily Irradiated Si Pad and Strip/Pixel Detectors: A Comparison Simulation Study 20mA simplified approach to compare quantitatively the contributions of electrons and holes to the total collected charge in heavily irradiated Si pad detectors and strip/pixel detectors has been developed in this study. By applying a step function to approximate the weighting field and a step function to approximate the linear- and/or double junction- electric field, in the detector, one can obtain analytical solutions of total collected charge and contributions from electrons and hole for irradiated Si detectors with various electric field and weighting field profiles combinations. Although the results do not exactly replicate the situation in a real detector, they qualitatively and quantitatively explain the contributions of electrons and holes in various detectors with different segmentation- and field-profiles.Speaker: Zheng Li (BNL)
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Collaboration Board Meeting
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Full detector systems
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09:05
Irradiation program in Prague - status. 20mIrradiation program in Prague is preparing on 2 possible way: on Cyclotron-based fast neutron facility at NPI Rez and in Experimental reactor at NRI, Rez. Basic conditions of this and plan for irradiation of ATLAS07 Series I large detectors will be presented .Speakers: Peter Kodys (Faculty of Mathematics and Physics), Dr Peter Kodys (Charles University)
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09:25
Comparison of the CCE properties of microstrip detectors made with different substrates and irradiated with protons and neutrons at different temperature 20mThe comparison of the charge collection properties of microstrip detectors made with FZ and MCz substrates are compared after irradiation with 26MeV and 24GeV/c protons and reactor neutrons. The lower energy proton irradiations took place at low temperature. The irradiations with the higher energy protons in the PS have been performed at room (>30oC) and cooled (about 0oC) T conditions. Their CCE performances are compared also with similar sensors irradiated at RT (~22oC, but shorter irradiation times) conditions in the nuclear reactor.Speaker: Affolder Anthony (University of Liverpool)
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09:45
Anneling of Charge Collection in Strip sensors and the Depletion Voltage 20mwe have irradiated n-type and p-type magnetic Czochralski and Float Zone silicon detector to proton, pion and neutron fluences up to 1.3*1015 neq/cm2. The data are collected right after irradiation and after elevated temperature annealing at 60oC, corresponding to several years of annealing at room temperature. As a function of bias voltage V, the following electrical parameters were measured: C-V at room temperature to extract the depletion voltage Vdep, and the charge collection efficiency in a beta source at lowered temperature to determine the “efficiency voltage”, i.e. the voltage at which the sensor becomes efficient at a threshold of 1 fC.Speaker: Hartmut Sadrozinski (SCIPP, UC santa Cruz)
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10:05
Neutron irradiation for p-type sensors. Detector characterization with ALIBAVA system 20mThis work describes the characterization of p-type microstrip detectors from two different manufacturers, Hamamatsu and CNM carried out at IFIC-Valencia. The sensors have been irradiated with neutrons at several fluences. In order to evaluate the macroscopic radiation damage, IV and charge collection measurements have been carried out by means of a radioactive source setup as well as by an infrared laser illumination. The sensors have been readout with the ALIBAVA system. It is a compact and a portable system which contains two front-end readout chips (Beetle chip) to acquire the detector signals. One of the advantages of the ALIBAVA system is that it uses LHC speed electronics. Another advantage is that it allows performing a pulse by pulse and strip by strip analysis.Speaker: Urmila Soldevila
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10:25
Coffee break 30m
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10:55
The avalanche effect in operation of heavily irradiated silicon p-i-n detectors 20mThe recent study of silicon detectors irradiated up to fluences beyond 10^15 neutron/cm^2 demonstrated an increase of the collected charge up to the value that is even higher than the charge initially generated by the detected particles. In the present investigation this effect is analyzed in terms of avalanche process in the abrupt p-n junctions. On the basis of double peak electric field distribution model developed earlier in the Ioffe institute, the dependence of the detector signal is calculated for different fluences and the detector operational bias. It is shown that the electric field distribution in heavy irradiated detectors is close or corresponds to the requirements for the avalanche process. In the case of short range particles the effect is more pronounced and can be observed. For MIPs detection it is suppressed by the spreading of generated pairs along the detector thickness ant therefore it requires higher bias voltage. The detector parameters which allow reaching an evident avalanche effect are defined and discussed in terms of detector operational environment and biasing conditions.Speaker: Vladimir Eremin (Ioffe Physical Technical Institute)
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11:15
Can we claim multiplication effects in irradiated silicon? 20mNew measurements to very high voltage are here shown that can give more support to the appearence of charge carrier multiplication effects in irradiated Micron silicon microstrip detectorsSpeaker: Gianluigi Casse (University of Liverpool)
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11:35
Measurements of lorentzangle in highly irradiated silicon-strip-detectors 20mThe planned SLHC-Upgrade will result in a 10 times higher luminosity and therefore higher radiation-damage to the silicon-detectors in the tracker-subsystem of CMS. The magnetic field inside the tracker causes a shift of chargecarriers inside the detector-silicon resulting in a displacement of the measured position to the real position of the particles track. The angle the carriers are shifted by is called the lorentzangle. In my diploma-thesis I measured lorentzangles in 3 materials: FZ-p-in-n, FZ-n-in-p and MCz p-in-n. The latter 2 were irradiated up to 10E16 neq/cm². Also, extensive measurements of non-irradiated sensors were done to compare the results with data from modells and simulations. The results of my work will be presented at this workshop.Speaker: Michael Schneider (University Karlsruhe)
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11:55
Performance of irradiated MCz detectors in a test beam environment 20mThe Silicon Beam Telescope (SiBT07) is a reference tracker used to characterize position sensitive detectors. I present selected testbeam results from irradiated MCz strip detector studies and discuss analysis methods associated with those results.Speaker: Teppo Maeenpaeae (Helsinki Institute of Physics HIP)
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Commissioning the CMS pixel detector with cosmic ray data 20mThe CMS Pixel detector, consisting of three barrel layers and two endcap disks at each barrel end, was installed in the CMS experiment in summer 2008. After a preliminary commissioning phase with pulse injections the detector participated in data taking with cosmic ray triggers and 3.8T field. We report on the first running experience with CMS and present preliminary results on detector performance. In addition, we discuss the detector performance after irradiation obtained from beam test measurements at CERN.Speaker: Prof. Vincenzo Chiochia (Universitat Zurich)
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12:40
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Lunch Break 1h 20m
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Defect and Material Characterization
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Prediction of the macroscopic "reverse annealing" using microscopic defect concentrations 20mIsothermal annealing studies were carried out at 80 °C on 75 um thick standard and oxygen enriched Epitaxial (EPI) material, irradiated with 1 MeV neutron fluences of 2E14 n/cm2 and 1E15 n/cm2. Depletion voltage and leakage current were obtained by CV and IV measurements while defect concentrations were measured by means of Thermally Stimulated Current technique (TSC). The microscopic results were used to predict the so called "reverse annealing". Our findings are in good agreement with the macroscopic sensor properties.Speaker: Alexandra Junkes (Hamburg University)
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15:05
Annealing induced evolution of defect centers in epitaxial silicon irradiated with high proton fluences 20mHigh-resolution photoinduced transient spectroscopy (HRPITS) has been used to studying the effect of isochronal annealing temperature on the properties defect centers in epitaxial silicon exposed to irradiation of 24 GeV/c protons with fluences ranging from 5x10^15 to 1.6x10^16cm^-2. The defect levels for standard and oxygenated epilayers have been compared. The main decrease in the concentrations of the defect centers in the both kinds of layers is observed after annealing at 160 oC. After annealing at 240 oC, the concentrations of midgap centers with activation energies of 420 meV and 535 meV, attributed to divacancies and higher order vacancies aggregates, are found to be approximately two times lower in the oxygenated epilayers than those in the standard epilayers.Speaker: Pawel Kaminski (Institute of Electronic Materials Technology)
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15:25
Coffee break 30m
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Comparative study of the electric field dependent variations of carrier recombination and drift parameters in MCZ Si detectors irradiated by different fluences of neutrons 20mSimultaneous measurements of the characteristics of photoconductivity transients, TOF, SCD (TCT) and SCLC by using various regimes of the surface and bulk excitation as well as current transient differential and integral registration regimes have been performed to clarify the electric field and neutron fluence dependent variations of carrier recombination and drift parameters in pad-detectors fabricated on MCZ Si. Significant changes of carrier drift time and of recombination with increase of fluence from 1012 to 1016 n/cm2 of the reactor neutrons have been obtained. However, carrier recombination lifetime is independent of the applied electric field at fixed irradiation fluence. It has been unveiled that current transients are determined by diffusion of light induced carrier domain at lowest values of applied voltage while these transients evolve via SCLC and SMD regimes to TOF transient with increase of electric field strength for low and moderate irradiation fluences. Changes of current transients due to variation of the carrier drift regimes are always observed within time scale of excess carrier density decay controlled by microwave probed photoconductivity transients. Peculiarities of extraction of material parameters at different regimes are discussed. Enhancement of excess carrier density with intensity of excitation tends to dominance of the diffusion of carrier domain and of the SCLC regimes at applied voltages up to full depletion of pin diode for fluences of <1015 n/cm2. Crucial shortening of carrier diffusion length at fluences > 1015 n/cm2 determines current transients which weakly depend on applied field. Analyze of the linear dependence of free carrier lifetime on fluence performed by modelling of clusters using the density functional theory. The calculated decrease of bandgap at the ring shape clusters (V6) demonstrate the importance of the local field for both carriers drift to the cluster and it causes the near to the linear decrease of the lifetime dependence on hadron fluence.Speaker: Prof. Juozas Vaitkus (Vilnius University)
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16:35
Effect of microscopic defects in n-type irradiated MCz silicon detectors: Impact on macroscopic parameters 20mIn order to study the effect of microscopic defects on macroscopic detector parameters, we have used synopsis T-CAD device simulator for four-level numerical modeling of radiation induced deep level traps using parameters obtained from experimental measurements. The resulting analysis techniques has been validated and calibrated by means of detailed comparison of the simulation with experimental measurements carried out on irradiated samples.Speaker: Dr Ajay Kumar Srivastava (UHH - Institut fuer Experimental Physik-Universitaet Hamburg-Un)
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Carrier lifetime variations in MCZ Si during irradiation by 3 - 8 MeV protons at temperatures in the range of 40 -300 K 20mVariations of carrier recombination lifetime, linearly dependent on radiation induced defects density, have been in situ examined during irradiations by stopped and penetrative protons in MCZ Si wafers of 350 m thickness. Irradiations and in situ lifetime measurements were performed at different stabilized temperatures in the range of 40 -300 K. Registration of the averaged carrier decay transients were carried out every second during exposure of a proton beam in remote mode over 15 m distant from vacuumated irradiation chamber by examination of microwave probed photoconductivity transients. Adjustments of the intersection at a boundary of wafer for the laser excitation beam transferred to a fiber spot and of the needle-tip microwave antenna have been performed by 3D stepper connected to irradiation chamber by flexible bellow system with lateral movement precision of ~ 2 m. Precision of adjustments were controlled remotely by using LAN interface and PC in safe area for measurements. Visual control of a location of probes within wafer thickness was also arranged by using optical fiberscope combined with VC. Probes were located at half-thickness of wafer under irradiation by penetrative protons, while these were positioned within stopping range for 3 MeV protons. Irradiation was kept for ~52000 counts or 15 – 20 min at 2 - 9 nA beam current. Carrier lifetime varied from 500 s to 0.5 ns over a complete exposure for initially non-irradiated material, while it changed from 1 s to 0.2 ns for 1012 p/cm2 pre-irradiated samples. Cross-sectional scans of carrier lifetime were performed just after irradiation. A lifetime reduction has been revealed within stopping range of 3 MeV protons. Carrier lifetime temperature variations in the range of 30 – 300 K had been examined before and after irradiations. Carrier decay transients appeared to contain several components caused by growth and radiation induced defects, which can be separated to recombination and carrier trapping centres. Spectrum of temperature variations of different carrier decay components enabled us to identify different defects. Rate of introduction of the radiation defects under proton beam exposure has been unveiled to be dependent on initial state and sample temperature during irradiation. More detailed analysis of evolution of radiation defects during irradiation by penetrative and stopped protons will be discussed.Speaker: Prof. Juozas Vaitkus (Vilnius University)
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Discussion Session 30m
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Workshop Dinner
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Pixel sensors, 3D and SOI detectors, Radiation Monitoring
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Status of the Planar Pixel Production at CiS 20mA production of Planar Pixel Sensors in the framework of the RD50 Collaboration is ongoing at CiS (Erfurt, Germany) in view of the pixel system upgrade of the ATLAS and CMS detectors for Super-LHC. The production is divided in two batches to investigate both the n-in-n and the n-in-p technologies. The sensors will be realized on Fz and MCz material. The designs for the two batches are completed and have been submitted to the producer. The layout of the wafers and the R&D plans to be carried out with these structures will be presented.Speaker: Anna Macchiolo (Max-Planck-Institut fuer Physik-Unknown-Unknown)
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09:20
Test Beam Measurements with 3D-ddtc Silicon Strip Detectors 20m3D double-sided double type column (ddtc) detectors were measured in a test beam at the CERN SPS in 2008. It was performed in the framework of RD50 and CMS and was provided by the University of Helsinki. The CMS silicon beam telescope and CMS tracker readout electronics were utilised. This talk focuses on a device under test produced by FBK-IRST (Trento). The current status of the analysis, which is done in collaboration with groups from Glasgow and Helsinki, is presented. The results comprise studies on spatially resolved charge collection and efficiency. A comparison with results obtained for 3D-stc (single type column) strip detectors shows the differences of the properties of the two designs.Speaker: Michael Koehler (University of Freiburg)
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09:40
Evaluation of novel pixel sensors for future tracking detectors 20mAn upgrade of the LHC towards a 10 times higher luminosity will require tracking detectors with unprecedented radiation tolerance. Furthermore, the high track density will call for fast and high granularity detectors, which also fulfill the boundary conditions of low radiation length and low costs. Over the last years several promising material developments and design concepts for the next generation of silicon pixel detectors have been brought forward. In the framework of Pixel Sensors R&D at CERN the noise and signal behavior for different sensor types has been studied with the goal of optimizing detector layout for their signal-to-threshold performance. The study included planar silicon sensors, 3D silicon sensors of different layout and manufactured by different producers as well as CVD diamond sensors. Details about the test results including for example comparative noise studies for different sensor types will be presented. Particular emphasis will be put on testing novel 3D-DDTC (Double side Double Type Columns) sensors produced by FBK/irst.Speaker: Alessandro La Rosa (CERN)
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coffee break 30m
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First characterizations of thin SOI and epitaxial n-in-p sensors 20mWe will present the results of first leakage-current and capacitance measurements of our 75 and 150 micron thin SOI production of n-in-p sensors before irradiation. They exhibit low dark currents and depletion voltages. A comparison between the performance of the standard and a reduced guard ring structure will be shown. Furthermore, the RD50 production of thin epitaxial n-in-p sensors, made by CIS, was characterized. Infrared pictures reveal signs of break downs in the inner guard rings as well as in the active area close to the bias ring.Speaker: Michael Beimforde (Werner-Heisenberg-Institut - Max-Planck-Institut fuer Physik)
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Online Radiation Dose Measurement System for ATLAS experiment 20mIn LHC experiments it will be important to continuously monitor the radiation doses to follow the level of degradation of detectors and electronics and to correctly predict future radiation damage. A system for online radiation monitoring using semiconductor radiation sensors was installed in the ATLAS experiment. Ionizing dose in SiO2 will be measured from increase of threshold voltage in p-MOS FET transistors ( RadFETs). The 1 MeV neutron equivalent fluences will be monitored from increase of forward voltage at given forward current in two types of p-i-n diodes and from measurements of increase of reverse current in 25 µm thick epitaxial pad diode. From measurements of degradation of current gain in dedicated transistors fluence of thermal neutrons will be estimated. In this contribution the system will be described and the results from long irradiation test in IRRAD6 at CERN will be shown.Speaker: Igor Mandic (Jožef Stefan Institute)
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Lunch break 1h 30m
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Discussion Session Pixel and New structures 20m
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