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This paper discusses the main results relevant to the characterization of an analog front-end processor designed in view of experiments with unprecedented particle rates and radiation levels at the high-luminosity Large Hadron Collider (HL-LHC). The front-end channel presented in this paper is part of the CHIPIX65-FE0 prototype, a readout application-specified integrated circuit designed in a 65-nm CMOS technology in the frame of the CERN RD53 collaboration. The prototype integrates a $64\times 64$ pixel matrix, divided into two $32\times 64$ submatrices, featuring squared pixels with 50- $\mu \text{m}$ pitch, embodying two analog front-end architectures based on synchronous and asynchronous hit discriminators. This paper is focused on the characterization of the array with asynchronous channels, before and after exposure to ionizing doses up to 630 Mrad(SiO2) of X-rays. The analog chain takes a per-channel area close to 1000 $\mu \text{m}^{2}$ , with a power dissipation of around 5 $\mu \text{W}$. The mean value of the equivalent noise charge, not significantly affected by radiation, is close to 100 electrons with no sensor connected to the front end. The threshold dispersion before irradiation is 55 electrons, for a tuned threshold of 600 electrons, with a moderate increase after irradiation. In-pixel analog-to-digital conversion, based on the time-over-threshold technique, is not appreciably influenced by the radiation as well. The assessed performance guarantees sub-1000 electrons stable threshold operations, which is a mandatory feature for highly efficient readout chips at the HL-LHC. [ABSTRACT FROM AUTHOR]

With technology scaling down, scale of the integrated circuit (IC) increases rapidly. It is unrealistic to harden every element in the IC, hence it is critical to evaluate relative single-event transient (SET) or single-event upset (SEU) sensitivity of each node in the IC to selectively harden the elements connected to the identified highly sensitive nodes. Therefore, this paper proposes a test circuit to measure the relative SET/SEU sensitivity of each node in any circuit working in real time. This will have significant implications for designing ICs with high reliability and low overheads. [ABSTRACT FROM PUBLISHER]

This paper presents a radiation tolerant phase-locked loop CMOS application-specified integrated circuit with an optimized voltage controlled oscillator (VCO) for single-event upsets (SEUs). The circuit is designed for high-energy particle physics experiments for low-jitter clock generation and clock recovery. An optimal tuning strategy of the VCO is presented that minimizes the cross section and the SEU sensitivity of the oscillator. The circuit is processed in a 65-nm CMOS technology and has been irradiated with heavy ions with a linear energy transfer between 10 to 69.2 MeV.cm2/mg. A comparison has been made with a conventional oscillator which proves a significant improvement in SEU sensitivity. [ABSTRACT FROM PUBLISHER]

The use of pulse-clocked latches has become ubiquitous in commercial unhardened integrated circuits (ICs) both for their performance and power benefits. In this paper, their use in soft-error hardened triple modular redundant (TMR) circuits is presented. The proposed multi-bit, self-correcting, TMR pulse-clocked latch macro provides a low power, high-speed design with high soft-error immunity. The macro includes test modes for delay testing of both individual and TMR copies with minimal area overhead, as well as a non-redundant operating mode. A physical design flow provides spatial separation of redundant logic copies to avoid upsets due to collection in multiple domains. A TMR, 128-bit data, 256-bit key, advanced encryption standard (AES) is fabricated on a 90-nm foundry low-standby power (LSP) process and its hardness verified using error injection simulations and proton beam testing. [ABSTRACT FROM PUBLISHER]

This paper reports numerical simulations of a three- dimensionally integrated, Boron-10 (10B) and Silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and 7Li) created from the neutron-10B reaction. In this paper, the effect of both the 3-D geometry (including pillar width, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated to compare well with the experimental data available at this time, for 7- and 12-μm tall micropillar arrays. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible. [ABSTRACT FROM AUTHOR]

This paper presents experimental data showing heavy ions inducing gate degradation in power MOSFETs. In the experiments, backside and front-side irradiations are performed. During backside irradiation, the heavy ion ranges are tuned in such way to control whether they hit the gate or not. Gate-to-source current loss (Φ) is measured versus heavy ions (H.I.) fluence Φ. Post-irradiation-gate-stress-test (PGST) allows measurement of gate breakdown voltage VBD (Φ) which is observed to decrease with (H.I.) fluence. Based on these experimental results, a hypothesis of substrate-generated carriers impact overlap of multiple strikes may explain gate degradation until SEGR triggering. This last hypothesis is supported by a statistical model approach of heavy ions multiple impacts. [ABSTRACT FROM AUTHOR]

We report on the design of a serializer ASIC to be used in the ATLAS forward muon detector for trigger data transmission. We discuss the performance of a prototype chip covering power dissipation, latency and stable operating line rate. Tests show that the serializer is capable of running at least at 5.76 Gbps with a bit error ratio below 1 \times 10^- 15, and a power consumption of 200 mW running at 4.8 Gbps. The latency between the start of loading 30 bits into the serializer to the transmission of the first bit from the serializer is measured to be about 6 ns. [ABSTRACT FROM AUTHOR]

The modular high-temperature gas-cooled nuclear reactor (MHTGR) is seen as one of the best candidates for the next generation of nuclear power plants. The once through steam generator (OTSG) is a crucial element for any MHTGR power plants with steam cycle. In order to guarantee the efficient and safe operation of the power plant, the outlet steam temperature of the OTSG should be well controlled. In this paper, a saturated output feedback dissipation control (SOFDC) law is presented for regulating the outlet steam temperature of OTSGs, and the corresponding robustness analysis is also given. In the numerical study, the SOFDC is applied to the outlet steam temperature control for the OTSG of Chinese high temperature gas-cooled reactor pebble-bed module (HTR-PM) project. Numerical simulation results show not only feasibility but also good control performance of this regulator, and the influence of its parameters to the regulation performance is also discussed. [ABSTRACT FROM AUTHOR]

Power-level regulation is a significant technique for guaranteeing both operation stability and efficiency of nuclear reactors. With the wide application of the digital instrument and control platforms, the implementation of modern state-feedback power control strategies, which have the ability of strengthening both the operation stability and efficiency for nuclear reactors, becomes much easier than before. Due to the advanced property of state-feedback power-level control and nonlinearity of reactor dynamics, it is so meaningful to develop nonlinear state-feedback power-level control laws. In this paper, a novel nonlinear state-feedback dissipation power-level control strategy is presented, which guarantees both the asymptotic closed-loop stability and convergent state-observation. Numerical simulation results show the feasibility and relationship between the observer-gain and control performance, and theoretic analysis corresponding to the simulation results is also given. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of the CoRoT CCDs dark current degradation measured during more than 2.5 years in orbit. Starting from on-ground irradiation results obtained during the space qualification of the detectors, a model is proposed to calculate the in-orbit pixel dark current distribution (including the hot pixels one). The modeling results are found to be in good agreement with the in-flight data. We therefore use this model to extrapolate the evolution of the dark signal distribution beyond 2.5 years. This is of primary interest in the context of a mission duration extension to 6 years proposed for the CoRoT mission. [ABSTRACT FROM AUTHOR]

This paper presents a study of the performance degradation in a proton environment of long wavelength infrared (LWIR) HgCdTe detectors. The energy dependence of the Non-Ionizing Energy Loss (NIEL) in HgCdTe provides a framework for estimating the responsivity degradation in LWIR HgCdTe detectors due to on-orbit exposure from protons. Banded detector arrays of different detector designs were irradiated at proton energies of 7, 12, and 63 MeV. These banded detector arrays allowed insight into how the fundamental detector parameters degraded in a proton environment at the three different proton energies. Measured data demonstrated that the detector responsivity degradation at 7 MeV is 5 times larger than the degradation at 63 MeV. Comparison of the responsivity degradation at the different proton energies suggests that the atomic Columbic interaction of the protons with the HgCdTe detector is likely the primary mechanism responsible for the degradation in responsivity at proton energies below 30 MeV. [ABSTRACT FROM AUTHOR]

A framework is presented for understanding carrier generation and recombination mechanisms in irradiated silicon devices. Data obtained by many workers for irradiated bulk material and devices are analyzed and summarized, and key damage-factor dependences are identified. Measurements, simulations, and analyses support the conclusion that correlation of displacement damage effects with the rate of nonionizing energy loss (NIEL) for proton, neutron, pion, and heavy-ion bombardment is due to the dominant influence of defect subclusters. At low NIEL values (< 5 × 10-5 MeV-cm²/g),isolated defects dominate the electrical properties. At relatively high NIEL (>2 × 10-4 MeV-cm²/g), subclusters dominate. Enhanced carrier generation and recombination produced by those small disordered regions is considered. Modeling results are presented for behavior observed in the transition region between domination by isolated defects and by clusters. The model presented in this paper simultaneously accommodates defect cluster models and NIEL scaling phenomena in the same framework. [ABSTRACT FROM AUTHOR]

In this paper, we compare the energy dependences (53 and 115 MeY) of proton displacement damage coefficients for p+ n GaAs solar cells with previously reported calculations of nonionizing energy loss (MEL). Deep level transient spectroscopy (DLTS) was used to generate damage coefficients from the introduction rates of defects. New damage coefficients generated from GaAs bulk LEDs light output (1-530 MeV) are also reported. The damage coefficients from these devices for proton energies E > 10 MeV vary but are bounded by the total and Coulombic MEL. [ABSTRACT FROM AUTHOR]

The test protocols for power MOSFETs used in the manufacturer's specification sheets are inadequate in that they do not represent a realistic worst-case condition. In addition, the applicable single-event effects (SEE) test methods and guidelines do not provide sufficient details to the user as to what conditions should be used, placing an undue burden on them. This paper addresses several of these deficiencies and others. We present a new test protocol; we suggest a new approach to describe the SEE response; and we provide a model to predict critical ion energies that should produce a worst-case response. [ABSTRACT FROM AUTHOR]

The electron induced nonionizing energy loss (NIEL) for representative device and detector materials are presented here. The electron NIELs are computed analytically using the Mott differential cross section. As for the partition function, which describes the portion of energy deposited into displacing lattice atoms, the expression recently developed by Akkerman et al. was used that better fits for the low recoil energy. [ABSTRACT FROM AUTHOR]

A method previously developed for proton non. ionizing energy loss (NIEL) calculations was extended to alpha particles. The alpha particle NIELs for representative device materials are presented from the damage threshold energy to 1 GeV/n. The method used the Ziegler, Biersack, Littmark (ZBL) screened potential for Coulomb interactions and the MCNPX "thin target approximation" for nuclear interactions. The alpha NIEL obtained in this study was compared to the proton NIEL from the previous study. It is seen that for silicon, the NIEL for alphas is about 16 dines the NIEL for protons at 1.0 MeV/n where the Coulombic interaction dominates. The ratio drops at higher energies because of the nuclear contributions. Furthermore, a simple radiation transport analysis indicates that in a representative space environment, the contribution of alphas to the damage dose can be comparable to the proton contribution, and that shielding has a marked influence on the relative contributions. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN)-based blue-emitting diodes (CREE Model C430-DH8S) were irradiated at room temperature with protons in the energy range 2 to 115 MeV at fluences varying from 1 × 1011 to 1 × 1015 cm-2. Light output degradation curves were obtained for each energy and the damage constant (A) associated with these curves was determined according to the theory of Rose and Barnes. For proton energies less than 10 MeV, A varies inversely with the proton energy (E). At higher energies, A is consistently above the 1/E relationship. The change in nature of the energy dependence is attributed to nuclear interactions. Nonionizing energy loss calculations for the case of protons on GaN are presented. Good agreement between theory and experiment is obtained. [ABSTRACT FROM AUTHOR]

We describe an analytical model for calculating nonionizing energy loss (NIEL) for heavy ions based on screened Coulomb potentials in the nonrelativistic limit. The model applies to any incident ion on any target material where the Coulomb interaction is primarily responsible for atomic displacement. Results are compared with previous methods of extracting NIEL from Monte Carlo SRIM runs. Examples of NIEL calculations are given for incident ions having energies ranging from the threshold for atomic displacement to 1 GeV. The incident ions Include H, He, B, Si, Fe, Xe, and Au. Example targets include Si, GaAs, InP, and SiC. [ABSTRACT FROM AUTHOR]

Calculates the degradation and life expectancy of five boron trifluoride detectors and a helium detector, using a method developed to measure the degradation of neutron detectors in neutron and gamma fields. Uses of boron trifluoride and helium detectors; Findings of the neutron and gamma ray tests; Discussion and analysis of the findings.

We have employed large-scale molecular dynamics simulations to study defect production, clustering, and its evolution in GaN for energies of a primary knock-on atom ranging from 500 eV to 40 keV. In the presence of proton radiation, a large number of atoms will be displaced during the collisional phase with a compacted cascade volume, but a great number of displaced atoms recombine significantly with vacancies at the same time, i.e., a pseudometallic behavior (PMB). This leads to the result that the majority of surviving defects are just single interstitials or vacancies for all recoil energies considered with only a small number of defects forming clusters. The total number of defects simulated in GaN can be very well predicted by the simplified Norgett, Robison, and Torrens (NRT) formula due to the PMB, in contrast to GaAs where the defect number becomes much larger than the NRT value. Moreover, the damage density within a cascade core is evaluated and applied to construct a model to calculate an energy-partition function for studying the nonionizing energy loss (NIEL) in GaN. The calculated NIEL in GaN is often found to be smaller than that predicted by a model based on the simple Kinchin–Pease formula. The comparisons of defect creation, density, and effective NIEL in GaN to those of GaAs suggest that GaN may be much more resistant to displacement damage than GaAs at low temperatures. [ABSTRACT FROM PUBLISHER]

In GaAs material, the radiation-induced degradations are demonstrated to vary according to the nonionizing energy loss (NIEL). But some discrepancies are still observed between experimental degradation measurements and predicted NIELs. The used displacement threshold energy varies, from one author to another, from 10 up to 25 eV. A measurement made with 60Co gamma rays is used to investigate the relevance of the NIEL scaling law for both electrons and gamma rays. [ABSTRACT FROM AUTHOR]

We present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits. [ABSTRACT FROM PUBLISHER]

The impact of high-Z metals on energy deposition in thin volumes due to direct ionization by ions in space environments is examined. The importance of energy loss straggling in small volumes typical of those found in advanced devices is also evaluated. It is found that direct ionization by protons over a large energy range may contribute significantly to error rates in advanced silicon on insulator devices due to energy loss straggling. This improves on conventional event rate analysis based on linear energy transfer, which does not describe the contributions of direct ionization by protons to the error rate. [ABSTRACT FROM AUTHOR]

Based on 2N2222 NPN bipolar junction transistors (BJTs), synergistic effect between ionization and displacement defects induced by 3 MeV, 5 MeV and 10 MeV protons were researched. High-energy protons can be incident upon the silicon (Si) BJTs, producing displacement defects in silicon bulk and ionization damage in the oxide layer of BJTs, respectively. Both ionization and displacement damage result in the degradation of current gain of BJTs. At a given displacement dose, 10 MeV protons induce the maximum degradation of current gain of 2N2222 NPN BJTs, while 3 MeV protons cause the minimum degradation. In this case, non-ionizing energy loss (NIEL) methodology is not suitable to normalize the displacement damage induced by 3 MeV, 5 MeV and 10 MeV protons, which is attributed to the synergistic effect of ionization and displacement damage. The displacement defect centers in based-collector junction of 2N2222 transistor induced by 3 MeV, 5 MeV and 10 MeV proton exposures, were discovered and characterized by deep level transient spectroscopy (DLTS). Based on the comparison between the electrical parameters and the DLTS results, it is shown that, interface traps due to ionization damage induced by high-energy protons spread the emitter-base depletion layer, leading to the enhancement effects to displacement damage in the base-collector junction of NPN BJT. Meanwhile, bias voltage used during DLTS measurement influence characteristics of DLTS signals. With the increasing reverse bias, the value of \Delta C/C for VO, V_2(= / -), E4 and V2(- /0) + E5 centers increases. [ABSTRACT FROM PUBLISHER]

Radiative relaxation channels and energy losses in In and Tl doped CsI scintillation crystals have been investigated as a function of temperature and excitation conditions to evaluate scintillation efficiency of the activator channel. Two activator concentration series of crystals were grown by the Bridgman method. Temperature dependence of excitation and luminescence spectra were measured under VUV and X-ray excitation; thermostimulated luminescence was also studied. The observed drop of radioluminescence yield of doped CsI crystals at room temperature relative to the pure crystal is explained by the migration losses caused by charge carrier trapping on the activator centers. The energy losses in CsI:A at low temperatures are due to the trapping of charge carriers on different centers: self-trapping of holes and capture of electrons by the activator centers. We suppose that migration energy losses are the main reason for significantly lower luminescence yield of CsI:A at room temperature than that of self-trapped excitons in pure CsI crystal [ABSTRACT FROM PUBLISHER]

We propose a low-power redundant flip-flop to be operated with high reliability over 1 GHz clock frequency based on the low-power (ACFF) and the highly-reliable (BCDMR) flip-flops. Its power dissipation is almost equivalent to the transmission-gate FF at 10% data activity while paying 3\times area penalty. Experiments by \alpha-particle and neutron irradiation reveal its highly-reliable operations with no error at 1.2 V and 1 GHz. We measured five different process corner chips by \alpha irradiation. Soft error rates are almost equivalent in these corner chips. [ABSTRACT FROM PUBLISHER]

We present VMM1, the first prototype of a family of front-end ASICs designed for the ATLAS muon upgrade. The ASIC will operate with MICROMEGAS and TGC detectors, providing charge and timing measurements along with other features including sub-hysteresis discrimination, address of the first event in real time, and digital output per channel for Time-over-Threshold measurements. The shaper, designed via the concept of Delayed Dissipative Feedback (DDF), supports analog dynamic ranges in excess of 10\thinspace000. With a capacitance of 200 pF and a nominal peaking time of 25 ns, the ASIC offers resolution of charge and timing better than 1 fC and 1 ns, respectively, for input charges up to 2 pC. Designed in a commercial 130 nm technology it dissipates about 4.5 mW per channel. [ABSTRACT FROM PUBLISHER]

Single particle displacement damage events are reported in silicon diodes irradiated with ^252Cf and ^241Am. In situ measurements of reverse current show the result of displacement damage incurred from individual fission fragments in ^252Cf irradiated diodes. Discrete increases in reverse current exceeding 20 fA are measured. The increases are temporally correlated with fission fragment-induced ionization events. The ratio of the damage factor associated with fission fragments to the damage factor associated with alpha particles is in good agreement with the ratio of non-ionizing energy loss calculated for fission fragments to NIEL calculated for alpha particles. [ABSTRACT FROM AUTHOR]

Using formvar films produced in our laboratory the influence on alpha PIPS spectrometry parameters, as energy shift, efficiency and resolution was investigated. The thickness of formvar films was estimated with the ASTAR web databases. No significant deterioration of the alpha spectrometry parameters was observed when using thin formvar films. Efficiency of the detection remains unchangeable and resolution decrease with 7% for a thickness of 50 \mug/cm^2. Alpha shift from spectrum can be used for measuring the thin foils. [ABSTRACT FROM AUTHOR]

BDD-IIR radiation environment detector data are used to calculate the expected solar array degradation for over 9 years of GPS orbit and compared with telemetered solar array data. The large discrepancy between the predicted and measured solar array output remains, thereby eliminating displacement damage as the sole damage mechanism to the solar arrays. [ABSTRACT FROM PUBLISHER]

The Variable Depth Bragg Peak (VDBP) method for measuring the Single Event Effects (SEE) cross-section of an integrated circuit (IC) in a closed package as a function of ion linear energy transfer (LET) is described. The method uses long-range, high-energy heavy ions that can penetrate the package and deposit charge in the device's sensitive volume (SV), the depth of which is not known. A series of calibrated energy degraders is used to vary the depth of the Bragg peak relative to the device's sensitive volume. When the Bragg peak is located at the sensitive volume, the measured SEE cross-section is a maximum, as is the LET, which is calculated using a Monte Carlo-based program, TRIM that takes both straggling and spread in beam energy and angle into account. Degrader thickness is varied and the change in LET is calculated while the corresponding cross-section is measured. Good agreement was obtained between the LET-dependence of the single event upset (SEU) cross-section for a 4 Mbit memory in an unopened package using the above method and that for an identical de-lidded part previously measured. [ABSTRACT FROM PUBLISHER]

We start with an analysis of the configurations commonly adopted to implement linear shapers. We show that, once the ENC from the charge amplifier is defined, the dynamic range of the system is set by the voltage swing and the value of the capacitance realizing the poles. The configuration used to realize the poles has also an impact, and those configurations based on passive components in feedback are expected to offer a higher dynamic range than the ones that use both active and passive components, like scaling mirrors. Finally, we introduce the concept of delayed dissipative feedback (DDF), which consists of delaying the resistive feedbacks from the furthest available nodes along the shaping chain. We will show that, in order to implement semi-Gaussian shapers, a small capacitor in positive feedback is required. The DDF technique can overcome some of the limitations of the more classical configurations. For example, in a third order shaper a factor of two higher dynamic range can be obtained or, at equal dynamic range, about 25% of the capacitance is needed (i.e. about 30% of the area in practical cases). [ABSTRACT FROM AUTHOR]

In contemporary control and data acquisition systems for Nuclear Fusion devices, the galloping need for high channel density and real-time multi-input-multi-output (MIMO) controller support gave rise to a new generation of hardware architecture based on the Advanced Telecommunications Computing Architecture (ATCA) specification. In addition, ATCA successfully delivered solutions in other sensitive issues like redundancy, power dissipation and available area for components and routing. Experience has shown, however, that such hardware devices can require a lengthy development. [ABSTRACT FROM PUBLISHER]

We present estimates of energy loss and charge sharing for a pixelated cadmium telluride (CdTe) detector used for photon-counting spectral computed tomography (CT). In a photon-counting pixelated CdTe detector, several physical effects lead to detected events with reduced energies, including Compton scattering, fluorescence emission, charge diffusion, trapping of charge carriers and slow-hole-motion-induced incomplete charge collection. Charge sharing is the result of the lost energy being collected by adjacent pixels. We simulated the photon transport and the charge-collection process with a Monte Carlo-based simulation and evaluated these effects on the detector performance. The trapping effect and poor hole collection have been studied together using an analytical model. We also investigated the detector response under the influence of only the fluorescence effect. We conclude that the charge sharing effects should be taken into account when the pixel is smaller than 1~\ mm^2. A straightforward way to decrease the double counting of X-rays from events with charge sharing is to increase the electronic threshold. However, increasing the threshold comes at the cost of losing low-energy events, which is undesirable, at least in applications such as pediatric imaging. [ABSTRACT FROM AUTHOR]

The non-ionizing energy loss (NIEL), often used to scale the damage coefficients of irradiated electronic components, sometimes fails to make good degradation predictions. The classical non-ionizing energy loss calculation, performed under binary cascade approximation, lacks accuracy at low incident energy for some light particles such as electrons. The amount of displacement damage predicted by molecular dynamics simulations where many-body interactions are naturally included can be signifi- cantly different from the classical binary collision calculation. The creation of damage predicted by molecular dynamics technique, within the low energy deposition regime, can be quite different from what can be classically simulated. For instance, earlier studies demonstrated that, under suitable conditions, low energy transfer below the atomic displacement threshold can increase damage production. In the case of silicon material, molecular dynamics simulation results have been incorporated within the definition of a new energy partition function. In comparison with the classical Kinchin Pease approach, our improved model more accurately estimates the number of displacements generated by a primary knock-on atom. This new energy partition function is used to calculate corrected non- ionizing energy loss. [ABSTRACT FROM AUTHOR]

The dependence of the subthreshold-swing (SS) degradation on fin width is reported for irradiated 100-nm-gatelength, fully depleted n-channel FinFETs. The wider the fin is, the greater the radiation-induced SS degradation. The higher tolerance to radiation-induced charge for the narrower FinFETs is attributed to the additional lateral gate control over the body potential. The irradiation and room temperature annealing results suggest that the SS increase for wider FinFETs is due primarily to nonuniform trapped charge in the buried oxide (BOX). The subthreshold characteristics of FinFETs with two fins are more likely to exhibit a nonuniform subthreshold slope (NUSS), resulting from fin-to-fin variability, than FinFETs with 20 fins, where the corresponding Id-Vgs curve is the composite of the 20 individual IdVgs curves. [ABSTRACT FROM AUTHOR]

An a-particle spectrometer has been assembled, consisting of an epitaxial 50 μm thick 4H silicon carbide (SiC) detector connected to a gallium-nitride (GaN) high-electron mobility transistor (HEMT) used as input transistor of the front-end electronics. The depleted layer of the SiC diode detector was sufficient to stop all a particles in the 4.8-MeV to 5.8-MeV energy range. An excellent energy resolution of ∼0.9 % has been obtained in this energy range at a temperature of 55 °C. The energy-resolution limiting factor is found to be the dispersion of the energy loss in the gold Schottky contact, which acts as entrance window to the detector. We used a GaN front-end transistor because this material offers two important advantages over silicon: 1) it is a wide bandgap semiconductor and therefore is intrinsically more desirable for room and above-room temperature operation and 2) it can be grown on SiC substrates so as to realize SiC/GaN integrated systems. SiC-detector spectrometers are interesting in many nuclear applications where the operation environment is hostile, both in terms of ionising radiations and of high temperatures. Such applications include monitoring of ionising radiations in nuclear power plants and beam diagnostic in fundamental nuclear physics experiments. [ABSTRACT FROM AUTHOR]

Displacement-damage induced degradation in AlGaN/AlN/GaN HEMTs with polarization charge induced 2DEGs is examined using simulations and experiments. Carrier removal in the unintentionally doped AlGaN layer changes the space charge in the structure and this changes the band bending. The band bending decreases the 2DEG density, which in turn reduces the drain current in the device. The effect of the defect energy levels on the 2DEG density is also studied. The interplay between carrier removal, mobility degradation, and the charged defects is analyzed and quantified. [ABSTRACT FROM AUTHOR]

Excitation spectra of CaF2, SrF2 and BaF2 crystals doped by CdF2, LaF3, YF3 in vacuum ultraviolet region were investigated at liquid-helium temperature and at room temperature. Spectra of doped BaF2 at low temperature and CaF2, SrF2 at room temperature show significant decrease of excitation intensity against those in undoped crystals while the intensities in exciton regions remain nearly the same. The common reason of the suppression of exciton emission by impurity in alkaline-earth fluorides is unradiative electron-hole re- combination on impurity sites. [ABSTRACT FROM AUTHOR]

Charge collection efficiency (CCE) of 6H-SiC diodes was evaluated before and after gamma irradiation using a Co-60 source. After gamma irradiation of 96 Mrad(SiC), CCE at a bias of 150 V decreased from 95% to 70%. The degradation of diffusion length of minority carriers was evaluated from the change in the applied bias dependence of CCE due to gamma irradiation. We also discuss whether non-ionizing energy loss (NIEL) analysis can be applied to evaluate the diffusion length degradation of 6H-SiC as well as the carrier removal rate. [ABSTRACT FROM AUTHOR]

The balloon-borne cosmic-ray experiment CREAM (Cosmic Ray Energetics And Mass) has completed two flights in Antarctica, with a combined duration of 70 days. One of the detectors in the payload is the SCD (Silicon Charge Detector) that measures the charge of high energy cosmic rays. The SCD was assembled with silicon sensors. A sensor is a 4 × 4 array of DC-coupled PIN diode pixels with the total active area of 21 × 16 mm ². The SCD used during the first flight (December 2004-January 2005) was a single layer device, then upgraded to a dual layer device for the second flight (December 2005-January 2006), covering the total sensitive area of 779 × 795 mm² Flight data demonstrated that adding a second layer improved SCD performance, showing excellent particle charge resolution. With a total dissipation of 136 W for the dual layer system, special care was needed in designing thermal paths to keep the detector temperature within its operational range. As a consequence, flight temperatures of the SCD, even at diurnal maximum were kept below 38° C. The SCD mechanical structure was designed to minimize the possibility of damage to the sensors and electronics from the impacts of parachute deployment and landing. The detector was recovered successfully following the flight and is being refurbished for the next flight in 2007. Details of construction, operation, and performance are presented for the dual-layered SCD flown for the second CREAM flight. [ABSTRACT FROM AUTHOR]

In the context of track reconstruction, the description of the material in a detector is frequently a simplified version of the detailed description used in the simulation. In particular, complex structures of different types of materials are often approximated by simple layers consisting of a material with average properties. Multiple scattering is then usually modeled by a Gaussian distribution, and energy loss by a narrow Gaussian or a delta function (Dirac distribution). More detailed information about the material can be taken into account by modeling multiple scattering and energy loss by mixtures of Gaussians and Dirac distributions, respectively. Each component of the mixture corresponds to a particular type of material, and the weight of the component is given by the probability to encounter this type of material. Track fitting using these mixtures can then be accomplished by the Gaussian-sum filter (GSF). Its performance is compared to a standard Kalman filter using the average material properties. The gain in precision of the estimated track parameters is studied in a series of simulation experiments, and the most promising scenarios are identified. [ABSTRACT FROM AUTHOR]

We compare differences in parametric degradation for CCDs irradiated to the same displacement damage dose with 2-MeV, 10-MeV, and 50-MeV electrons. Charge transfer efficiency degradation was observed to not scale well with non-ionizing energy loss (NIEL) for small signals. Short term annealing of mean dark current in a CCD sample irradiated with 2-MeV electrons at -85C is discussed, as well as additional annealing achieved by warming to temperatures up to and including room temperature. In contrast, charge transfer inefficiency was not observed to anneal following room temperature cycling for the sample irradiated at -85C. [ABSTRACT FROM AUTHOR]

The analysis of Lindhard's calculations of the partition factor Q and the corresponding factor obtained from the SRIM calculations shows that both significantly underestimate the energy losses to damage for ions below 100 keV. This is the result of their overestimation of the electronic losses of such ions in matter. New partition factor for low energy (<500 keV) ions in silicon is calculated by a specially developed Monte Carlo code. The new Q-values are significantly larger than previous results. This brings them to a good agreement with the experimental data including recently published precise ionization measurements using silicon based photodiodes. We used the new partition factor for calculating the non-ionizing energy losses (NIEL) for electrons and protons. The resulted NIEL values are larger by 15% on the average compared to the published calculated data. [ABSTRACT FROM AUTHOR]

While calculated non-ionizing energy loss (NIEL) generally correlates well to first order with radiation-induced displacement damage rates, it does not account for some well-known differences in damage rates for n. and p-type Si. Here we show that the magnitude of these differences, ΔKn-p, correlates closely with the fraction of total displacement damage due to low-energy primary knock-on atom (PKA) recoils. The primary products of these displacement damage events, with PKA recoils <∼ 2 keV, are close vacancy-interstitial pairs, or Frenkel Pairs (FPs). Based on previous studies of vacancy-dopant complex stabilities in Si, and new parameter-free quantum mechanical calculations of FP properties, details of the stable defect profiles arising from low-energy PKA recoil events are shown to give rise to non-zero values of ΔKn-p. [ABSTRACT FROM AUTHOR]

N-channel trigate SOI MOSFETs have been irradiated with 60Co gamma rays at doses up to 6 Mrad(SiO2). The threshold voltage shift at 6 Mrad is less than 10 mV in transistors with a gate length of 0.3 μm. At 6 Mrad(SiO2), the current drive reduction in the same devices is 10% if VG = 0 V during irradiation and 20% if VG = 1 V during the irradiation. The generation of positive charges in the BOX increases the electron concentration at the bottom interface of the silicon fins. Inversion electrons at the bottom interface have a higher mobility than the electrons at the (110)-oriented fin sidewalls. As a result, an increase of transconductance with dose is observed at moderate doses [<1 Mrad(SiO2)]. At higher doses, the usual mobility degradation caused by interface trap generation is observed. [ABSTRACT FROM AUTHOR]

The impact of the bias condition during irradiation on the total-dose response of a bipolar voltage comparator is investigated. Experimental results obtained with input pins biased asymmetrically during irradiation exhibit completely different total-dose response compared to irradiation with all pins grounded. Circuit analysis shows that asymmetrical biasing of the input stage creates a mismatch of the gain degradation in the transistors constituting the differential pair. [ABSTRACT FROM AUTHOR]

The semiconductor nuclear detector structure is usually a superposition of several different layers: the metallic electrode, the interface, the depleted zone, the nondepleted one, and finally the second electrode. All inactive layers, and particularly the "dead layer" region below the metallic electrodes, give rise to absorption for photons (X, γ) and to energy loss for charged particles. As a consequence, the detectors measure lower count rates for photons, particularly at low energies, and lower energies for charged particles. The amount of this effect can be only partially attributed to the inactive metallic electrode; the main part has to be attributed to the highly defected zone below the electrode in the interfacial region. This is a structural drawback which needs to be studied to reduce this effect, e.g., by developing new polishing and deposition techniques, or to perform the appropriate corrections. We have measured the thickness of this dead layer for various solution dilution electroless depositions of Pt electrodes on CdTe devices. These measurements were carried out by using collimated (X, γ) rays beams impinging at different angles, especially the grazing ones, and comparing the count rates registered at two selected angles, and by measuring Rutherford backscattering spectra and energy loss of 4He ions. [ABSTRACT FROM AUTHOR]

An index that would reliably rank the relative radiation hardness of semiconductors would be very helpful for selecting materials for many applications. The concept of "concentration of primary defects" (CPD) has been proposed as such an index. Here we show that for the GaAs-InP family of semiconductors used in solar cells, CPD yields results that do not agree with experiment. The long-established concept of damage constants for various semiconductor properties is a more reliable index. For solar cells the relevant damage constant is that for the degradation of minority carrier lifetime. Although the damage constants reported for different semiconductors are specific to a particular type and energy of radiation, we show they can be extended beyond the type and particle energy for which they were originally determined by using nonionizing energy loss (NIEL), thereby greatly extending their possible application. [ABSTRACT FROM AUTHOR]

Proton irradiation decreases the doping concentration and increases the ideality factor and series resistance, but has very little effect on the Schottky barrier height in n-Gallium nitride Schottky diodes. 1.0-MeV protons cause greater degradation than 1.8-MeV protons because of their higher nonionizing energy loss. The displacement damage recovers during annealing. Comparison between Schottky diodes and high electron-mobility transistors suggests that the degradation in both types of devices is predominantly due to carrier removal and mobility degradation caused by radiation-induced defect centers in the crystal lattice, with interface disorder playing a relatively insignificant part in overall device degradation. [ABSTRACT FROM AUTHOR]