Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCharge collection characterisation with the Transient Current Technique of the ams H35DEMO CMOS detector after proton irradiation
70
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
This paper reports on the characterisation with Transient Current Technique measurements of the charge collection and depletion depth of a radiation-hard high-voltage CMOS pixel sensor produced at ams AG. Several substrate resistivities were tested before and after proton irradiation with two different sources: the 24 GeV Proton Synchrotron at CERN and the 16.7 MeV Cyclotron at Bern Inselspital.
rate research
Read More
GaAs Schottky diode detectors have been fabricated upon Low Pressure Vapour Phase Epitaxial GaAs. The devices were characterised before and after a $1.25 times 10^{14}$~cm$^{-2}$ 24GeV/c proton fluence. The as fabricated Ti-GaAs barrier height was measured, via two electrical methods, to be $0.81pm0.005$ and $0.85pm0.01$~eV and a space charge density of $2.8 pm 0.2 times 10^{14}$~cm$^{-3}$ was determined. The current was greater than that expected for an ideal barrier with the excess attributed to generation current from the bulk. The charge collection efficiency, determined from front alpha illumination and 60 keV gamma irradiation, was inexcess of 95% at 50V reverse bias. After irradiation the reverse current, measured for a bias of 200V at 20$^{o}$~C, increased from 90~nA to 1500~nA due to radiation induced generation centres. Deep levels were showed to be present using capacitance techniques. The charge collection of the device determined from front alpha illumination fell to $32pm5$% at a reverse bias of 200V.
Monolithic active pixel sensors produced in High Voltage CMOS (HV-CMOS) technology are being considered for High Energy Physics applications due to the ease of production and the reduced costs. Such technology is especially appealing when large areas to be covered and material budget are concerned. This is the case of the outermost pixel layers of the future ATLAS tracking detector for the HL-LHC. For experiments at hadron colliders, radiation hardness is a key requirement which is not fulfilled by standard CMOS sensor designs that collect charge by diffusion. This issue has been addressed by depleted active pixel sensors in which electronics are embedded into a large deep implantation ensuring uniform charge collection by drift. Very first small prototypes of hybrid depleted active pixel sensors have already shown a radiation hardness compatible with the ATLAS requirements. Nevertheless, to compete with the present hybrid solutions a further reduction in costs achievable by a fully monolithic design is desirable. The H35DEMO is a large electrode full reticle demonstrator chip produced in AMS 350 nm HV-CMOS technology by the collaboration of Karlsruher Institut fur Technologie (KIT), Institut de Fisica dAltes Energies (IFAE), University of Liverpool and University of Geneva. It includes two large monolithic pixel matrices which can be operated standalone. One of these two matrices has been characterised at beam test before and after irradiation with protons and neutrons. Results demonstrated the feasibility of producing radiation hard large area fully monolithic pixel sensors in HV-CMOS technology. H35DEMO chips with a substrate resistivity of 200$Omega$ cm irradiated with neutrons showed a radiation hardness up to a fluence of $10^{15}$n$_{eq}$cm$^{-2}$ with a hit efficiency of about 99% and a noise occupancy lower than $10^{-6}$ hits in a LHC bunch crossing of 25ns at 150V.
Edge-TCT and charge collection measurements with passive test structures made in LFoundry 150 nm CMOS process on p-type substrate with initial resistivity of over 3 k$Omega$cm are presented. Measurements were made before and after irradiation with reactor neutrons up to 2$cdot$10$^{15}$ n$_{mathrm{eq}}$/cm$^2$. Two sets of devices were investigated: unthinned (700 $mu$m) with substrate biased through the implant on top and thinned (200 $mu$m) with processed and metallised back plane. Depleted depth was estimated with Edge-TCT and collected charge was measured with $^{90}$Sr source using an external amplifier with 25 ns shaping time. Depleted depth at given bias voltage decreased with increasing neutron fluence but it was still larger than 70 $mu$m at 250 V after the highest fluence. After irradiation much higher collected charge was measured with thinned detectors with processed back plane although the same depleted depth was observed with Edge-TCT. Most probable value of collected charge of over 5000 electrons was measured also after irradiation to 2$cdot$10$^{15}$ n$_{mathrm{eq}}$/cm$^2$. This is sufficient to ensure successful operation of these detectors at the outer layer of the pixel detector in the ATLAS experiment at the upgraded HL-LHC.
High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) based on the 180 nm HV-CMOS process have been proposed to realize thin, fast and highly integrated pixel sensors. The MuPix7 prototype, fabricated in the commercial AMS H18 process, features a fully integrated on-chip readout, i.e. hit-digitization, zero suppression and data serialization. It is the first fully monolithic HV-CMOS pixel sensor that has been tested for the use in high irradiation environments like HL-LHC. We present results from laboratory and test beam measurements of MuPix7 prototypes irradiated with neutrons (up to $5.0cdot10^{15}{,rm{n}_{rm{eq}}/cm^2}$) and protons (up to $7.8cdot 10^{15} ,rm{protons}/cm^2$) and compare the performance with non-irradiated sensors. Efficiencies well above 90 % at noise rates below 200 Hz per pixel are measured. A time resolution better than 22 ns is measured for all tested settings and sensors, even at the highest irradiation fluences. The data transmission at 1.25 Gbit/s and the on-chip PLL remain fully functional.
We study the radiation effects of the Low Gain Avalanche Detector (LGAD) sensors developed by the Institute of High Energy Physics (IHEP) and the Novel Device Laboratory (NDL) of Beijing Normal University in China. These new sensors have been irradiated at the China Institute of Atomic Energy (CIAE) using 100 MeV proton beam with five different fluences from 7$times10^{14}$ $n_{eq}/cm^2$ up to 4.5$times10^{15}$ $n_{eq}/cm^2$. The result shows the effective doping concentration in the gain layer decreases with the increase of irradiation fluence, as expected by the acceptor removal mechanism. By comparing data and model gives the acceptor removal coefficient $c_{A}$ = $(6.07pm0.70)times10^{-16}~cm^2$, which indicates the NDL sensor has fairly good radiation resistance.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
