Charge Collection Measurements Research Articles

Development of a beam test telescope based on the Alibava readout system

A telescope for a beam test have been developed as a result of a collaboration among the University of Liverpool, Centro Nacional de Microelectrónica (CNM) of Barcelona and Instituto de Física Corpuscular (IFIC) of Valencia. This system is intended to carry out both analogue charge collection and spatial resolution measurements with different types of microstrip or pixel silicon detectors in a beam test environment.The telescope has four XY measurement as well as trigger planes (XYT board) and it can accommodate up to twelve devices under test (DUT board). The DUT board uses two Beetle ASICs for the readout of chilled silicon detectors. The board could operate in a self-triggering mode. The board features a temperature sensor and it can be mounted on a rotary stage. A peltier element is used for cooling the DUT.Each XYT board measures the track space points using two silicon strip detectors connected to two Beetle ASICs. It can also trigger on the particle tracks in the beam test. The board includes a CPLD which allows for the synchronization of the trigger signal to a common clock frequency, delaying and implementing coincidence with other XYT boards.An Alibava mother board is used to read out and to control each XYT/DUT board from a common trigger signal and a common clock signal. The Alibava board has a TDC on board to have a time stamp of each trigger. The data collected by each Alibava board is sent to a master card by means of a local data/address bus following a custom digital protocol.The master board distributes the trigger, clock and reset signals. It also merges the data streams from up to sixteen Alibava boards. The board has also a test channel for testing in a standard mode a XYT or DUT board. This board is implemented with a Xilinx development board and a custom patch board. The master board is connected with the DAQ software via 100M Ethernet. Track based alignment software has also been developed for the data obtained with the DAQ software.

The Effect of High-Z Materials on Proton-Induced Charge Collection

Charge collection measurements reveal that the presence of high-Z materials increases proton-induced charge collection cross sections for high charge collection events. The mechanism for this effect is proton-induced fission events as shown through validated Monte Carlo simulations. These fission fragments are emitted isotropically in contrast to high-LET secondary particles from proton-silicon interactions which tend to be forward directed.

Novel Energy-Dependent Effects Revealed in GeV Heavy-Ion-Induced Transient Measurements of Antimony-Based III-V HEMTs

High-bandwidth (16 GHz) time-resolved charge-collection measurements for heavy-ion irradiation of up to 70 GeV/amu are performed on low-power 6.1 Å lattice spacing InAlSb/InAs HEMT devices. Event cross sections are measured to be significantly larger than the active areas of the devices. Novel energy-dependent effects are observed.

Collected charge of planar silicon detectors after pion and proton irradiations up to 2.2 ×1016 neq cm−2

The planned luminosity upgrade of the Large Hadron Collider at CERN (Super-LHC) will provide a challenging environment for the tracking and vertexing detector systems. Planar, segmented silicon detectors are one of the few radiation tolerant technologies under consideration for use for the Super-LHC tracking detectors in either pixel or strip geometries. In this paper, charge collection measurements are made with planar silicon sensors with 2 different substrate materials (float zone and magnetic Czochralski) and 3 different diode configurations (p+ strip in n-bulk, n+ strip in n-bulk, and n+ strip in p-bulk).For the first time, a comparison of the charge collection of these devices will be made after irradiation up to 6 ×1014neqcm−2 with 280MeV charged pions, and up to 2.2 ×1016neqcm−2 with 26MeV protons. This study covers the expected range of final fluences for the different layers of pixel and microstrip sensors of the ATLAS and CMS experiments at the Super-LHC. These measurements have been carried out using analogue, high-speed (40MHz) electronics and a Strontium-90 beta source.

Position Resolution for the CMS Barrel Pixel Detector after Irradiation

The CMS barrel pixel detector is the innermost tracking device, reconstructing the interaction vertices and charged particle trajectories. At the LHC design luminosity, 10 34 cm − 2 s − 1 , there will be 1000 charged particles per bunch crossing every 25 ns. In the innermost layer the pixel sensors will be exposed to a fluence of 3 × 10 14 n eq / cm 2 / yr with consequent degradation of the silicon lattice structure and particle detection performances. Beam tests of irradiated pixel sensors were performed at CERN with the final front end electronics in a 3T magnetic field. We present the measurements of charge collection and radiation hardness, as well as spatial resolution.

Charge Generation by Secondary Particles From Nuclear Reactions in BEOL Materials

Direct charge collection measurements are presented, which prove that the presence of tungsten near sensitive volumes leads to extreme charge collection events through nuclear reactions. We demonstrate that, for a fixed incident particle linear energy transfer (LET), increasing particle energy beyond a certain point causes a decrease in nuclear reaction-induced charge collection. This suggests that a worst-case energy exists for single-event effect (SEE) susceptibility, which depends on the technology, device layout, and the incident ions' fixed LET value. A Monte Carlo approach for identifying the worst-case energy is applied to certain bulk-Si and silicon-on-insulator (SOI) technologies. Simulation results suggest that the decrease in charge collection beyond the worst-case energy occurs because the secondary particles produced from the high-energy nuclear reactions have less mass and higher energy and are therefore less ionizing than those produced by lower-energy reactions.

Comparison of pad detectors produced on different silicon materials after irradiation with neutrons, protons and pions

A set of 44 pad detectors produced on p- and n-type MCz and Fz wafers was irradiated with 23 GeV protons, 200 MeV pions and reactor neutrons up to the equivalent fluences of Φ eq = 3 × 10 15 cm - 2 . The evolution of the full depletion voltage and the leakage current were monitored during short- and long-term annealing. At selected representative annealing steps, charge collection measurements were performed for all samples with LHC speed electronics. Measurements of full depletion voltage, leakage current and charge collection efficiency were compared for different irradiation particles and silicon materials.

Beam-test results of 4k pixel CMOS MAPS and high resistivity striplet detectors equipped with digital sparsified readout in the Slim5 low mass silicon demonstrator

The results obtained by the Slim5 collaboration on a low material budget tracking silicon demonstrator put on a 12 GeV/ c proton test beam at CERN are reported. Inside a reference telescope, two different and innovative detectors were placed for careful tests. The first was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130 nm CMOS Technology, square pixels 50 μ m wide, thinned down to 100 μ m and equipped with a digital sparsified readout running up to 50 MHz. The other was a high resistivity double sided silicon detector, 200 μ m thick, with short strips with 50 μ m pitch at 45 ∘ angle to the detector's edge. The detectors were equipped with dedicated fast readout architectures performing on-chip data sparsification and providing the timing information for the hits. The criteria followed in the design of the pixel sensor and of the pixel readout architecture will be reviewed. Preliminary measurements of the pixel charge collection, track detection efficiencies and resolutions of pixel and strip sensors are discussed. The data driven architecture of the readout chips has been fully exploited in the test beam by a data acquisition system able to collect on electronic board up to 2.5 Million events per second before triggering. By using a dedicated Associative Memory board, we were able to perform a level 1 trigger system, with minimal latency, identifying cleanly tracks traversing the detectors. System architecture and main performances are shown.

Analysis of deep level parameters in irradiated silicon detectors

Both the collected charge and the capacitance of a silicon detector are proportional to the depleted depth of the space charge region. The presence of deep levels introduces frequency dependence in the measured capacitance, and this frequency dependence can be corrected for by analyzing the data using admittance spectroscopy. An equivalent circuit for a PN junction containing deep levels is used to accurately model deep level response. Activation energy, majority carrier cross-section and the concentration of active deep levels at the edge of the space charge region is determined. Space charge region depth as a function of the applied voltage is extracted for various detectors irradiated with neutrons and pions. When possible, depleted depths are compared to charge collection measurements.

Observation of full charge collection efficiency in heavily irradiated n+p strip detectors irradiated up to 3×10 15 n eq/cm 2

In this work we report measurements of signals caused by fast electrons from a 90Sr source detected by n-type readout strips implanted in p-type bulk silicon, read out with a SCT128 chip. Charge collection measurements with detectors irradiated with reactor neutrons up to 10 16 n eq/cm 2 were performed up to very high reverse bias voltages of over 2000 V. The most probable value of collected charge measured with detectors irradiated up to 3×10 15 n eq/cm 2 was as high as that measured before irradiation. Detectors irradiated to 10 16 n eq/cm 2 also exhibited very good performance. Because of the large resistance of the heavily irradiated silicon detectors they can be biased with a high forward voltage, allowing charge collection measurements to also be performed in the forward bias mode of operation. Simulations of charge collection in an irradiated detector were compared to measurements.

Charge Collection Efficiency Measurements of Heavily Irradiated Segmented n-in-p and p-in-n Silicon Detectors for Use at the Super-LHC

The planned luminosity upgrade of the Large Hadron Collider at CERN (Super-LHC) will provide a challenging environment for the tracking and vertexing detector systems. With a proposed nearly 10-fold luminosity increase to 1035 cm2 middot s-1, the innermost devices will have to be able to withstand a hadron dose on the order of 1times1016 1 MeV neutron equivalent per square centimeter over the anticipated five year lifetime of the experiments. Planar, segmented silicon detectors with n-strip readout are one of the radiation tolerant technologies under consideration for use for the Super-LHC tracking detectors in either pixel or strip geometries. This paper details measurements made with n-strip (n-in-p) and p-strip (p-in-n) planar devices that have been irradiated to doses as high as 1times1016 neq cm-2 with reactor neutrons and fast protons. The doses under study cover the expected range of final fluences for the different tracking systems of the ATLAS and CMS experiments at the Super-LHC. The charge collection measurements have been carried out using analogue, high-speed (40 MHz) electronics and a Strontium electron source. These measurements show that p-in-n sensors are not radiation tolerant enough for the requirements of the micro-strip detectors at the SLHC; whereas, the charge collection properties exhibited by the n-in-p strip devices may be sufficient for all tracker regions (pixels and strips) of the SLHC assuming that appropriate low noise and threshold readout electronics are designed and adequate bias voltage can be routed to the sensors.

Laser Verification of On-Chip Charge-Collection Measurement Circuit

An on-chip charge-collection measurement circuit has been designed and fabricated in a 130 nm bulk CMOS process. Laser testing is used to verify the effectiveness of the on-chip charge-collection circuit technique for characterizing single event charge collection in advanced technologies. The on-chip charge-collection measurement circuit is used as an investigative tool for examining the effects of parasitic bipolar amplification for deep-submicron PMOS devices.

Charge-Collection and Single-Event Upset Measurements at the ISIS Neutron Source

Charge-collection measurements at the VESUVIO instrument at ISIS are described. Neutron SEU cross sections in SRAM-based FPGAs are measured. Results are compared to equivalent data from Los Alamos Neutron Science Center ICE House. The rate of single-event effects due to fast neutrons at VESUVIO is approximately 15% of that at LANSCE. In addition there is a strong thermal and epithermal component, sufficient to cause many events in devices containing small amounts of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> B. The effects of low-energy neutrons on a commercial CCD contaminated with traces of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> B are described. Cadmium shielding is found to be incompletely effective in separating the effects of fast and slow neutrons, and the implications for testing protocols and instrument design are discussed.

Aspects of Photocatalysis on Semiconductors: Photoelectrocatalysis

An overview is given of the essential processes governing heterogeneous photocatalysis on semiconductor surfaces. It is shown that the reactions on the surface of the catalyst are of electrochemical nature and can be described using electrochemical principles. This leads to a quantitative description of the processes. In combination with measurements of charge collection yields and Faradaic efficiencies, or product quantum yields, the reaction rates can be calculated when the spectral dependence of the intensity of the light source is known. Examples are given for transition metal oxide semiconductors such as titanium dioxide and tungsten trioxide.

Design and performance of the silicon sensors for the CMS barrel pixel detector

The CMS experiment at the (LHC) includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The barrel region consists of n-in-n sensors with 100 × 150 μ m 2 cell size processed on diffusion oxygenated float zone silicon. A biasing grid is implemented and pixel isolation is achieved with the moderated p-spray technique. An extensive test program was carried out on the H 2 beam line of the CERN-SPS. In this paper we describe the sensor layout, the beam test setup and the results obtained with both irradiated and non-irradiated prototype devices. Measurements of charge collection, hit detection efficiency, Lorentz angle and spatial resolution are presented.

Transient Response of Semiconductor Electronics to Ionizing Radiation. Recent Developments in Charge-Collection Measurement

Recent measurements of heavy-ion-induced charge- collection transients are presented. These measurements are possible for the first time because of recent developments in high- bandwidth, single-shot measurement technology, and exhibit several significant advantages over conventional (charge-sensitive preamplifier) charge-collection measurements. Heavy-ion induced transient measurements are presented for InGaAs/InAlAs HEMTs, AlSb/InAs HEMTs, GaAs HFETs and for SOI NMOS devices, and the significant advantages of this approach are described.

Charge collection measurements with p-type Magnetic Czochralski silicon single pad detectors

The charge collected from beta source particles in single pad detectors produced on p-type Magnetic Czochralski (MCz) silicon wafers has been measured before and after irradiation with 26 MeV protons. After a 1 MeV neutron equivalent fluence of 1 × 10 15 cm - 2 the collected charge is reduced to 77% at bias voltages below 900 V. This result is compared with previous results from charge collection measurements.

Charge collection measurements in single-type column 3D sensors

We report on charge collection studies on 3D silicon detectors of single-type column n-diffusions in p-substrate, configured either as strip or as pad detectors. The charge is generated by penetrating beta particles from a 90Sr source which, together with a scintillation counter, serves as an electron telescope. The charge collection as a function of bias voltage is compared with the depletion thickness derived from the measured C– V characteristics.

Measurement of the transient response of semiconductor devices to ionizing radiation

Recent developments in the measurement of heavy-ion induced charge-collection transients of semiconductor devices are described. The information content of transient SET measurement is significantly enhanced relative to that of conventional charge-collection measurement. Examples of recent measurements on InP HEMT and SOI NMOS devices are presented.

Application of Imaging Systems to Characterization of Single-Event Effects in High-Energy Neutron Environments

We use charge-coupled devices (CCDs) to characterise the single-event effect (SEE) inducing properties of high-energy neutron beams, including the spatial distribution of induced charge. Three representative CCD types are evaluated for this purpose. We study the significance of anti-blooming structures and pixel size. Anti-blooming structures are found to suppress event rates and corrupt event statistics. Devices without such structures are preferred and anti-blooming correction is performed in software. A CCD with 9 mum pixels is chosen for an Imaging SEE Monitor, which is currently being deployed in a variety of natural and synthetic neutron fields. Comparison is made between effects observed in neutron beams at LANSCE and TRIUMF accelerator facilities. Cross-sections for all events at the two facilities agree, providing independent confirmation of dosimetry. Cross-sections for more intense events disagree, with about a factor of 5 difference (LANSCE more effective) at 1 pC deposited charge. We attribute this discrepancy to the harder neutron spectrum at LANSCE, and conclude that predictions of SEE cross-sections in devices of interest, as measured at the two facilities, are liable to differ for this reason. Predictions of SEE rates in the field may also be in doubt. Charge collection measurements are recommended for adoption in test protocols for accelerated testing for neutron SEE