The photoconductivity and mobility of carriers was investigated in highly irradiated Si. The measurements were performed in microstrip samples at different temperature and different bias, up to high electric field regime. It was observed decrease the mobility with increase of fluence. The photoconductivity spectra demonstrated the main defects and its filling, and an increase of surface...
Phosphorus and Boron doped profiles of silcion wafers have been investigated to reconstruct active doping profile from Transmission line measurements. It is known that total doping profiles is accessible through Secondary Ion Mass spectrometry analysis. Here this methods enable us to determine electrical active doping profiles and see the change of this concentration after irradiation ....
Non-ionising energy loss of radiation produces point defects and defect cluster in silicon, which result in a significant performance degradation of detectors. In this contribution we present results of defect spectroscopy using TSC (Thermally Stimulated Current) measurements on silicon pad diodes irradiated by electrons of different energies, where significantly different ratios of point to...
We present the ionizing energy depositions in a 300 $\mu$m thick silicon layer after fast neutron impact. With the Time-of-Flight (ToF) technique, the ionizing energy deposition spectra of recoil silicons and secondary charged particles were assigned to (quasi-) monoenergetic neutron energies in the range from 180 keV to hundreds of MeV. We show and interpret representative measured energy...
We present a study of electrically active radiation-induced defects formed in 4H-SiC epitaxial layers following irradiation with fast neutrons, 600 keV H+ and 2 MeV He++ ion implantations. The Schottky barrier diodes (SBD) were formed by evaporation of nickel through a metal mask with patterned quadratic apertures of 1 mm × 1 mm, while Ohmic contacts were formed by nickel sintering at 950 °C...
Nitrogen enriched wafers have shown some improvement after irradiation. NitroStrip is an RD50 project that has fabricated p-in-n wafers with four different materials, FZ, DOFZ, nitrogen enriched and MCz. Here we will show measurements of unirradiated and some irradiated detectors.
Acceptor removal has been studied on a set of p-type sensors irradiated with protons up to 7E15 neq/cm2. Two sets of diodes were used: thin epitaxial diodes with different resistivities (10, 50, 250 and 1000 Ohm cm) and high resistivity float zone diodes with different thicknesses (100, 150, 200 and 285 um).
CV, IV and TCT measurements were performed to extract the effective doping...
In the framework of monolithic active silicon sensors (MAPS), a new fabrication process that consists in bonding a CMOS wafer on a high resistivity silicon bulk which is used as the active sensor is investigated. In this way, it is possible to optimize both the read-out electronics and the sensing element. The electrical properties of the bonding interface are therefore important, since the...
This presentation will report on latest Two-Photon Absorption-TCT measurement campaigns carried out within 2 on-going RD50-projects, namely measurements of diodes and HVCMOS devices. The presentation will then focus on recent measurements of proton irradiated LGAD detectors, showing a clear double junction after 1e14 neq/cm2. Some other systematics of TPA measurements encountered so far will...
We present a theoretical model to predict the plasma delay time in the signal generated by the Two Photon Absorption technique and a confrontation with real measurements.
https://indico.cern.ch/event/681859/
The worldwide fusion community has been developing understanding of plasma physics and
fusion plasmas due to the development of theoretical models, rapid advances in computer
simulation techniques and pioneering work in plasma diagnostics. A large fraction of such know-
how is derived from a complete suite of spectroscopic and particle diagnostics. It is thus crucial
to maintain the...
Avalanche Photo Diodes (APDs) produced by Radiation Monitoring Devices are examined as candidate timing detectors for HL-LHC applications.
These APDs are operated at 1.8 kV, resulting in a gain of up to 500.
The timing performance of the detectors is evaluated using a pulsed laser.
The effects of radiation damage on current, signal amplitude, noise, and timing of the APDs are evaluated...
In view of the future HL-LHC upgrade, a variety of technologies are being considered for particle tracking. One of these technologies is Deep Diffused APDs (DD-APDs). Several DD-APDs were characterised through CV/IV and TCT measurements before and after neutron irradiation. The irradiation took place at the Jožef Stefan Institute (Ljubljana, Slovenia). The fluences to which the devices were...
We will discuss mainly gain and timing resolution of thin LGAD both before and after neutron irradiation.
In the past year, the CMS and ATLAS collaborations have defined the detector geometry of their respective timing layers. Even though both collaborations have selected UFSD in their baseline design, the requirements for the two experiments differ in key aspects such as with pixel size, radiation hardness, number of layers. In this contribution we review the requirements and challenges in the...
Over the last few years, Fondazione Bruno Kessler, in collaboration with the universities of Trento and Turin, has been involved in developing of Silicon sensors with low internal gain, the so-called Ultra-FAST Silicon Detectors (UFSD). Such a detector is based on the concept of Low-Gain Avalanche Detectors (LGAD), which are silicon detectors with an internal, low multiplication mechanism...
AC-LGAD are LGAD with simplified structure.
Basically all segmentation in the P+, N+ and oxide are eliminated and only the AC-coupled metal contact is segmented.
We have tested with laser, beta and alpha the first prototypes from CNM Run 10478 which were produced without optimization of the doping profile and simulated the response with TCAD and SPICE. A program going forward is described.
An in-deep study of a p-in-p LGAD prototype (dubbed as I-LGAD) is presented. Contrary to the conventional LGAD devices, currently proposed for the HL-LHC mip timing detectors, the I-LGAD has a non-segmented deep p-well ( the multiplication layer). Therefore, I-LGADs should idealy present a constant gain value over all the sensitive region of the device without gain drops between the signal...
The advantages TCAD based studies offer during the development of semiconductor sensors are multiple: they are predictive, they provide insight
and they capture and visualise theoretical knowledge.
In this talk I will report on Silvaco TCAD Atlas Device simulator, in particular about the modelisation of the most fundamental semiconductor
physics parameters in that tool, the band gap energy...
TCAD simulation has become a valuable tool in the design and understanding process of silicon sensors for high energy physics applications. The predictive power is limited by the uncertainties arising from different available semiconductor physics models but also from the simulation software itself.
In this talk we will present a comparison between Silvaco and Synopsys predictions for...
The impact of the active base with a low electric field on the bulk current in Si detectors irradiated to F ≥ 1x10^15 neq/cm2, i.e. to fluences of interest for the experiments at HL-LHC was studied. The simulated profiles of the electric field E(x) and of the bulk current densities j(x) showed that active base gives different contribution to the detector current operating as electrically...
Due to internal charge multiplication, Low Gain Avalanche Detectors (LGAD) enable to produce rather thin (~ 50 µm) silicon sensors with a relatively low operating voltage. A typical P-type LGAD consists of n+-p-p–p+ layers with p-well formed by deep diffusion of boron into p– layer. Another way of p-well formation by using an epitaxial process may lead to lower sensitivity of the breakdown...
TRACS is a C++11 based software that carries out an effective calculation of the induced current over irradiated and non-irradiated silicon microstrip and pad detectors. Its new achievements and developments will be presented.
A study of Silicon pixel sensors of size 50 um x 50 um fabricated at CNM using double-sided 3D technology is presented. Sensors are bump-bonded to the pixelated ROC4Sens read-out chip which exactly matches the sensor geometry. We analyze the response of two hybrid assemblies in a test beam of 5.6 GeV electrons. Results of charge collection, charge sharing, spatial resolution and efficiency are...
A new generation of CNM 3D pixel sensors with small pixel sizes of 50x50 and 25x100 $\mu$m$^{2}$ and reduced electrode distances are developed for the HL-LHC upgrade of the ATLAS pixel detector. For the first time, pixel detectors are irradiated and studied up to the unprecedented fluence of 2.5$\times10^{16} n_{eq}$/cm$^2$, i.e. for the full expected HL-LHC life time to explore the limits of...
P-type sensors have been selected as a base material for many future detectors due to the superior radiation hardness. The properties and performance of irradiated sensors has been intensively measured, but some aspects like the annealing behavior are still under evaluation.
In this contribution long term annealing studies at room temperature and 60°C on ATLAS12 p-type mini strip sensors,...
The innermost tracking detector of the ATLAS experiment consists of planar n-in-n silicon pixel sensors. Closest to the beam pipe lays the insertable b-layer (IBL). Its pixels are arranged in a pitch of 250um x 50um, with a rectangular shaped n-implant.
Based on this design six modified pixel designs have been developed in Dortmund.
The new pixel designs are arranged in structures of ten...
Facing the high luminosity phase of the LHC (HL-LHC) to start operation around 2026, a major upgrade of the tracker system is in preparation for the ATLAS experiment. Thanks to the small material budget and their high charge collection efficiency after irradiation, thin planar pixel modules are the baseline option to instrument all layers of the pixel system beginning from the second layer.
To...
The increased LHC luminosity as well as maximal particle energy require more precise data on the intensity of radiation field at the magnet coils of collider. For that the radiation sensors must be placed in the proximity of the coils, which minimizes the fraction of debris in beam loss monitoring. Silicon sensors were chosen as one of the candidates and the related R&D was started six years...
In 2016 PSI developed a pixel readout chip dedicated to sensor studies. It provides a full alanalogue signal without zero suppression, but needs a fast (~100ns) external trigger and has some speed limitations. The array is 160 x 155 pixels with a pitch of 50 Micrometer in both directions. A simple readout system based on the CMS pixel digital test board has been designed which was used in test...
I will present test results of OVERMOS1, a MAPS CMOS detector based on high resistivity substrate. Following a short description of the main features of OVERMOS1 and differences with respect to previous OVERMOS incarnation, I will describe experimental results of test structures, both for standard and neutron irradiated devices, and comparisons with TCAD simulation results.
Active silicon sensors produced in CMOS technology are commonly manufactured on substrates of intermediate resistivity and are usually operated under partial depletion. Irradiation and consequent effective acceptor removal changes the depletion depth and therefore the amount of collected charge.
We will present a study of proton irradiation effects in the fluence range of 4e14 - 4e15 neq/cm2...
High Energy Particle Physics experiments at the LHC use hybrid silicon detectors, in both pixel and strip geometry, for their inner trackers. These detectors have proven to be very reliable and performant. Nevertheless, there is great interest in the development of depleted CMOS silicon detectors, which
could achieve similar performances at lower cost of production and complexity.
Studies of...
The ATLAS experiment is planning a major upgrade of its tracking detectors during the Phase-II LHC shut down, to better take advantage of the increased luminosity that will be provided by the HL-LHC. New depleted CMOS sensors are being developed for this upgrade. Preliminary results of the evaluation of TowerJazz 180nm CMOS sensors using the Edge-Transient Current Technique (Edge-TCT) are...
Depleted Monolithic Active Pixel Sensors (DMAPS) built with High Voltage CMOS (HV-CMOS) technology are investigated as an option to cover large areas in the outermost layers of the future pixel detector of the ATLAS Inner Tracker (ITk) at HL-LHC.
The H35Demo is a large area HV-CMOS demonstrator prototype chip developed for the ITk which features a large fill factor layout with 25x250 um^2...
As the HV-CMOS technology is emerging as a prime candidate for many future experiments in particle physics, it is a priority for the RD50 collaboration to develop and study particle detectors in this technology. In this context, the collaboration has started a new effort to design and manufacture dedicated test structures and matrices of HV-CMOS and HV-MAPS pixels. Two HV-CMOS submissions are...
