Displacement Damage Dose Research Articles

Equivalent Displacement Damage Dose for On-Orbit Space Applications

The calculation of the displacement damage dose (DDD) in a material is not often as straightforward as simply combining the particle fluence and the nonionizing energy loss (NIEL) but often requires a consideration of the degradation parametrics of a particular microelectronic device. This paper defines an Equivalent Displacement Damage Dose (EDDD) which is more representative of the degradation of the device. Displacement damage radiation effects in solar cells will be used to illustrate the model.

Evaluation and prediction of the degradation of space Si solar cells induced by a low-earth-orbit radiation environment

Space-graded silicon solar cells are evaluated by 1 MeV and 2 MeV electron-irradiation. The mean degradation of the maximum power (Pmax) is presented and analyzed. The degradation at both electron energies has been correlated with the displacement damage dose (Dd). A good linearity between the electron Dd and the mean Pmax degradation is obtained. The concept of Dd has also been used to predict the Si solar cell response in a low-earth-orbit (Altitude 799 km, Inclination 99°) radiation environment, considering the shielded effect of a 120 μm-thick silica coverglass on reducing the radiation. Compared with the on-orbit data from a Si solar array of a Chinese satellite (duration from April 2007 to July 2010), a good match can be found between the on-orbit data and the predicted results using Dd methodology, indicating the method is appropriate for evaluating the radiation damage of the solar cells, and also to provide a new technique for studying radiation effects on the optoelectronic detectors used in many high energy physics applications, where harsh radiation environments produce damage in optoelectronic device materials.

Ion irradiation of electronic-type-separated single wall carbon nanotubes: A model for radiation effects in nanostructured carbon

The structural and electrical properties of electronic-type-separated (metallic and semiconducting) single wall carbon nanotube (SWCNT) thin-films have been investigated after irradiation with 150 keV 11B+ and 150 keV 31P+ with fluences ranging from 1012 to 1015 ions/cm2. Raman spectroscopy results indicate that the ratio of the Raman D to G′ band peak intensities (D/G′) is a more sensitive indicator of SWCNT structural modification induced by ion irradiation by one order of magnitude compared to the ratio of the Raman D to G band peak intensities (D/G). The increase in sheet resistance (Rs) of the thin-films follows a similar trend as the D/G′ ratio, suggesting that the radiation induced variation in bulk electrical transport for both electronic-types is equal and related to localized defect generation. The characterization results for the various samples are compared based on the displacement damage dose (DDD) imparted to the sample, which is material and damage source independent. Therefore, it is possible to extend the analysis to include data from irradiation of transferred CVD-graphene films on SiO2/Si substrates using 35 keV C+ ions, and compare the observed changes at equivalent levels of ion irradiation-induced damage to that observed in the SWCNT thin-film samples. Ultimately, a model is developed for the prediction of the radiation response of nanostructured carbon materials based on the DDD for any incident ion with low-energy recoil spectra. The model is also related to the defect concentration, and subsequently the effective defect-to-defect length, and yields a maximum defect concentration (minimum defect-to-defect length) above which the bulk electrical transport properties in SWCNT thin-films and large graphene-based electronic devices rapidly degrade when exposed to harsh environments.

Similarities Between Proton and Neutron Induced Dark Current Distribution in CMOS Image Sensors

Several CMOS image sensors were exposed to neutron or proton beams (displacement damage dose range from 4 TeV/g to 1825 TeV/g) and their radiation-induced dark current distributions are compared. It appears that for a given displacement damage dose, the hot pixel tail distributions are very similar, if normalized properly. This behavior is observed on all the tested CIS designs (4 designs, 2 technologies) and all the tested particles (protons from 50 MeV to 500 MeV and neutrons from 14 MeV to 22 MeV). Thanks to this result, all the dark current distribution presented in this paper can be fitted by a simple model with a unique set of two factors (not varying from one experimental condition to another). The proposed normalization method of the dark current histogram can be used to compare any dark current distribution to the distributions observed in this work. This paper suggests that this model could be applied to other devices and/or irradiation conditions.

Pyrolytic carbon free-radical evolution and irradiation damage of polyimide under low-energy proton irradiation

Ionization and displacement effects are basic phenomena in damage processes of materials under space-particle irradiation. In this paper, the damage behaviors were investigated on the polyimide under proton irradiation using electron paramagnetic resonance (EPR) spectra analysis and optical absorbance valuation. The results indicate that the proton irradiation induces the formation of pyrolytic carbon free-radical with a g value of 2.0025, and the population of free radicals increases with the irradiation fluence. The most important finding is that the irradiation-induced free-radical population increases linearly with the displacement damage dose, as does the optical degradation, whereas the ionization effect alone, during the irradiation, cannot induce the formation of pyrolytic carbon free radical. Furthermore, during the post storage, after irradiation, the free-radical population decreases following a sum of an exponential and a linear mode with the storage time. It is interesting that, during the post storage, the recovery of the degraded optical absorbance of the polyimide follows a similar mode to that of free radicals, and the characteristic time constant changes with the wavelength of the optical spectra.

Total Ionizing Dose Versus Displacement Damage Dose Induced Dark Current Random Telegraph Signals in CMOS Image Sensors

Dark current Random Telegraph Signals due to total ionizing dose (TID) and displacement damage dose (DDD) are investigated in CMOS image sensors. Discrepancies between both RTS are emphasised to better understand the microscopic origins of the phenomena.

Displacement damage dose used for analyzing electron irradiation-induced degradation of GaInP/GaAs/Ge space solar cells

Displacement damage dose (Dd) approach was applied to analyze the electron irradiation-induced degradation of GaInP/GaAs/Ge space solar cells by effective 1 MeV electron Dd, the electron irradiation-induced maximum power Pmax degradation of the solar cells is plotted as a function of the effective 1 MeV electron Dd, and the result shows that all the measured electron data can be represented by a single curve using displacement damage dose. Obviously, the displacement damage dose approach simplifies the description of electron irradiation-induced degradation of GaInP/GaAs/Ge space solar cells, and also offers an alternative for handling the case where degradation occurs as a result of combined electron and proton irradiation.

An original DoE-based tool for silicon photodetectors EoL estimation in space environments

In our previous works we have demonstrated that Design of Experiments (DoE) is an innovative methodology defining optimized irradiation test plan and particularly valuable for the space qualification of silicon photodetectors. In particular, it provided us with the degradation model of photocurrent, darkness current, and spectral responsivity of silicon based phototransistors arrays with respect to the Total Ionizing Dose (TID) and to the Displacement Damage Dose (DDD), over a wide range of space-mission profiles. In this paper, we will summarize at first main results obtained thanks to the DoE methodology. Then we present how we can easily obtain, by exploiting DoE collected data, End-of-Life predictions of such devices with a reduced number of experiments, with a small batch of devices, and in relatively short time.

Low cycle fatigue properties of reduced activation ferritic/martensitic steels after high-dose neutron irradiation

This paper focuses on the low cycle fatigue (LCF) behaviour of reduced activation ferritic/martensitic steels irradiated to a displacement damage dose of up to 70 dpa at 330–337 °C in the BOR 60 reactor within the ARBOR 2 irradiation programme. The influence of neutron irradiation on the fatigue behaviour was determined for the as-received EUROFER97, pre-irradiation heat-treated EUROFER97 HT and F82H-mod steels. Strain-controlled push–pull loading was performed using miniaturized cylindrical specimens at a constant temperature of 330 °C with total strain ranges between 0.8% and 1.1%. Comparison of the LCF behaviour of irradiated and reference unirradiated specimens was performed for both the adequate total and inelastic strains. Neutron irradiation-induced hardening may have various effects on the fatigue behaviour of the steels. The reduction of inelastic strain in the irradiated state compared with the reference unirradiated state at common total strain amplitudes may increase fatigue lifetime. The increase in the stress at the adequate inelastic strain, by contrast, may accelerate fatigue damage accumulation. Depending on which of the two effects mentioned dominates, neutron irradiation may either extend or reduce the fatigue lifetime compared with the reference unirradiated state. The results obtained for EUROFER97 and EUROFER97 HT confirm these considerations. Most of the irradiated specimens show fatigue lifetimes comparable to those of the reference unirradiated state at adequate inelastic strains. Some irradiated specimens, however, show lifetime reduction or increase in comparison with the reference state at adequate inelastic strains.

First In-Flight Data Analysis of Displacement Damage on the OSL Sensor On-Board CARMEN-2

Displacement damage dose was measured over 26 months on the CARMEN-2 experiment using the feedback loop of an Optically Stimulated Luminescence (OSL) sensor. These in-flight results are analyzed and discussed addressing the issue of temperature dependence and energy correction. A comparison between in-flight data and ground tests measurement validates this method.

Adjusted NIEL calculations for estimating proton-induced degradation of GaInP/GaAs/Ge space solar cells

The non-ionizing energy loss (NIEL) values for protons in solar cells should be modified by taking into account the distribution of the Bragg damage peak in the active region to calculate the corresponding displacement damage dose. In this paper, based upon a thin target approximation, a new approach is presented to modify NIEL values for protons on a GaAs sub-cell. Adjusted NIEL values can be used to estimate the degradation induced by protons on GaInP/GaAs/Ge triple-junction space solar cells.

Probability of divacancy trap production in silicon diodes exposed to focused ion beam irradiation

We present ion beam induced charge (IBIC) measurements of the critical displacement damage dose Dd values and modeling of the probability of divacancy trap production in p+−n−n+ silicon diodes exposed to megaelectron volt energy ion beam irradiation. The normalized induced charge (Q0/Q) measured by He ion probe in tested silicon diodes irradiated by focused He, Li, O, and Cl ion beams with energies of about 0.3 MeV/u increases linearly with Dd according to the modified radiation damage function and nonionizing energy loss (NIEL) theory. A simple IBIC model based on Gunn theorem showed clear dependence of the induced charge Q and corresponding equivalent damage factor Ked value on both a depth profile of charge created by ionizing particle (probe) and a depth distribution of stable defects created from primary defects produced by damaging ions. The average probability of the divacancy production (defined as the ratio of the final electrical active defect quantity and primary ion induced vacancy quantity for each impinging ion) of 0.18 (18%) was calculated by the IBIC modeling for all damaging ions.

Radiation damage of space GaAs/Ge solar cells evaluated by displacement damage dose

In this paper,the degradation of irradiated GaAs/Ge single junction (SJ) solar cells is evaluated under the orbital environments using the displacement damage dose method. Firstly the electric-property changes of the SJ solar cells are experimentally obtained with the fluencies of electrons and protons of various energies under ground-based irradiation simulators. Based on the experimenal results and the calculated non-ionization energy losses (NIELs) of the electrons and protons in GaAs, the equivalent exponent n is obtained to be 1.7 for various electron energies,while the equivalent coefficient Rep for electron displacement damage converted into that of protons is 5.2. Furthermore, a degradation formula of the electrical property of the domestic SJ solar cell is established as a function of displacement damage dose during the particle irradiation. Using the displacement damage technique, the orbital evolution of the electric property degradation of the domestic SJ cell is predicted in this paper. In the meantime, the shielding effects of the cover glass with different thicknesses are also evaluated.

Displacement Damage Characterization of Electron Radiation in Triple-Junction GaAs Solar Cells

The effect of space radiation environments on the degradation of triple-junction InGaP2/GaAs/Ge cells was studied to provide the reference for solar array design. The irradiationswere performedby the irradiation line-based unit-6 electron radiation facility. The solar cells were irradiated at room temperature with 0.8, 1, and 2 Mev electrons. For a given degradation level, the fluence level decreases for an increasing energy, indicating the higher energy electrons do relatively more damage. Degradation at different electron energies has been correlated with displacement damage dose. The performance of the triple-junction cells with various thicknesses of silica coverglass in a geostationaryEarth orbit radiation environment is presented. The power of the triple-junction cells will decrease to about 60%of the original value if uncovered by silica glass, while the use of a 500m-thick glass will decrease the endpower of the 15-yearmission by 30%of the original power. A 100m-thick silica glass (thickness usually used in space solar array) is not enough for blocking the electron radiation on the solar cells.

Analysis of Displacement Damage Dose and Low Annealing Temperatures on the I-V Characteristics of SiC Schottky Diodes Using ANOVA Method

Silicon carbide (SiC) is a promising semiconductor material for use in solid-state radiation detectors. SiC’s wide bandgap makes it an appropriate semiconductor for high-temperature applications. Because of the annealing process that occurs at temperatures above 150°C for SiC, SiC semiconductors may function in a radiation environment for longer periods of time at elevated temperatures than at room temperature. Unlike thermal annealing effects that can act to improve the electrical characteristics of SiC, fast neutrons create displacement damage defects in SiC Schottky diodes through scattering and thus rapidly degrade the electrical properties of the SiC diodes.We irradiated SiC Schottky diodes at the Ohio State University Research Reactor at room temperature with neutrons for displacement damage doses (Dd’s) ranging from 7.6 × 1010 to 3.8 × 1011 MeV/g. After irradiation, we annealed the diodes, at either 175 or 300°C. We measured the SiC diodes’ forward bias resistances at different steps of the experiments. To perform the experiments and study the results meaningfully, we performed a full factorial design of experiments with two factors: Dd and annealing temperature. The Dd factor had five levels of treatment, and the temperature had three levels of treatment. We did one-way and two-way analysis of variance to understand which factor is more dominant and whether or not the interaction effects are significant. It was determined that for Dd up to 2.3 × 1011 MeV/g the fractional damage recovery decreases with increasing Dd, but that Dd is not a significant factor affecting further changes in damage recovery for Dd’s ranging from 2.3 × 1011 to 3.8 × 1011 MeV/g when the annealing temperature varies between 175 and 300°C. For high Dd (greater than 2.3 × 1011 MeV/g) neutron irradiations, the annealing temperature significantly affects the damage recovery.

Microstructural evolution in irradiated uranium-bearing delta-phase oxides A 6U 1O 12 (A = Y, Gd, Ho, Yb, and Lu)

Irradiation-induced microstructural evolution in uranium-bearing delta-phase oxides of A 6U 1O 12 (A = rare earth cations) were characterized using grazing incidence X-ray diffraction and transmission electron microscopy. Polycrystalline Y 6U 1O 12, Gd 6U 1O 12, Ho 6U 1O 12, Yb 6U 1O 12, and Lu 6U 1O 12 samples were irradiated with 300 keV Kr ++ to a fluence of 2 × 10 20 ions/m 2 at cryogenic temperature (∼100 K). The crystal structure of these compounds was determined to be an ordered, fluorite derivative structure, known as the delta-phase, a rhombohedral symmetry belonging to space group R 3 ¯ . Experimental results indicate that all these compounds are resistant to amorphization to a displacement damage dose of ∼60 displacements per atom. In these experiments, we sometimes observed an irradiation-induced order-to-disorder phase transformation, from an ordered rhombohedral to a disordered fluorite structure.

Order-to-disorder transformation in δ-phase Sc4Zr3O12 induced by light ion irradiation

Polycrystalline δ-phase Sc4Zr3O12 was irradiated with 200 keV Ne+ ions at cryogenic temperature to fluences ranging from 2 × 1018 to 1 × 1021 Ne/m2. Irradiation-induced structural evolution was examined by using grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy. An order-to-disorder (O-D) crystal structure transformation (from an ordered δ-phase to a disordered, fluorite phase) was observed to initiate by a fluence of 2 × 1018 Ne/m2, corresponding to a peak ballistic damage dose of ∼0.075 displacements per atom. This displacement damage dose is much lower than the O-D transformation dose threshold found in previous heavy ion irradiation experiments on δ-Sc4Zr3O12 [J.A. Valdez et al., Nucl. Instrum. Methods B250, 148 (2006); K.E. Sickafus et al., Nat. Mater.6, 217 (2007)]. In this study, we contrast the O-D transformation efficiency of the light Ne ions used in these experiments, to the heavy (Kr) ions used previously, and interpret the differences in terms of enhanced damage efficiency for light ions (greater fraction of surviving defects per defect produced). To better quantify this surviving defect phenomenon, we also present new, additional ion irradiation results on δ-Sc4Zr3O12, obtained from 300 keV Kr2+ and 100 keV He+ ion irradiation experiments.

Radiation effects in single-walled carbon nanotube papers

The effects of ionizing radiation on the temperature-dependent conductivity of single-walled carbon nanotube (SWCNT) papers have been investigated in situ in a high vacuum environment. Irradiation of the SWCNT papers with 4.2MeV alpha particles results in a steady decrease in the SWCNT paper conductivity, resulting in a 25% reduction in room temperature conductivity after a fluence of 3×1012 alpha particles/cm2. The radiation-induced temperature-dependent conductivity modification indicates that radiation damage causes an increase in the effective activation barrier for tunneling-like conductivity and a concomitant increase in wavefunction localization of charge carriers within individual SWCNTs. The spatial defect generation within the SWCNT paper was modeled and confirms that a uniform displacement damage dose was imparted to the paper. This allows the damage coefficient (i.e., differential change in conductivity with fluence) for alpha particles, carbon ions, and protons to be compared with the corresponding nonionizing energy loss (NIEL) of the incident particle. The resulting nonlinear relationship with NIEL between these parameters is distinct from the more typical linear response observed in many bulk semiconductors and superconductors and indicates that localized radiation damage in the SWCNT papers has a greater impact than distributed damage. Although SWCNT papers behave largely as a bulk material with properties that are a convolution of the underlying SWCNT distribution, the radiation response appears to be largely dominated by degradation in the preferred one-dimensional conduction within these two-dimensionally confined nanostructures.

Space radiation environment forecast for EGYPTSAT‐2 satellite

The space environment provides an assortment of hazards whose ill effects can range from degraded performance up to catastrophic loss of a spacecraft. The radiation environment is believed to be the most significant in terms of spacecraft failures. Hence, the present work provides a radiation analysis for the EGYPTSAT‐2 which is supposed to be launched in 2012 as a low Earth orbit satellite in order to assist the EGYPTSAT‐2 instrument team with adequate planning decisions. AE‐8, AP‐8, Jet Propulsion Laboratory (JPL) model, and the cosmic ray effects in microelectronic (CREME86) code are used to estimate the fluences of the trapped electrons and protons, solar protons, and galactic cosmic protons, respectively. SHIELDOSE‐2 code is used for space‐shielding radiation dose calculations, and the nonionizing energy loss function is used to estimate the nonionizing dose of space radiation. Finally, the end‐of‐life solar cell performance is evaluated using the displacement damage dose (DDD) method. The slowed down spectra emerging from the shielding material is obtained using the Multilayered Shielding Simulation Software (MULASSIS) code. It has been found that the radiation environment will not impede the sensitivity of EGYPTSAT‐2 materials over the course of the baseline mission lifetime. For 1.5 mm aluminum shielding thickness, total ionizing dose is 2.65 × 104 rads (Si) and DDD is 7.75 × 107 MeV/g(Si) for 5 years mission length, which are less than critical thresholds. Also, a flat glass of SiO2 sheet of thickness 0.5 mm is enough to resist the damage effect of the solar array cells.

Capacitor-based isolation amplifiers for harsh radiation environments

Commercial-off-the-shelf (COTS) capacitor-based isolation amplifiers were irradiated at the Portuguese Research Reactor (PRR) in order to determine its tolerance to the displacement damage and total ionising dose (TID). The set of experimental data shows that some of these devices are suitable for zones inside future nuclear facilities where the expected total radiation damage would be below 2.2 × 10 13 1 ‐ MeV neutron / cm 2 and 230 Gy (Si). However, some drawbacks must be taken into account by the electronic designers such as the increase of the output offset voltage and the slight modification of the transmission gain.