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Experimental characterization through electron paramagnetic resonance (EPR) and confocal luminescence microscopy (CML) of a Ge-doped glass (preform and fiber) reveals the generation of several point defects by 10 keV X-ray radiation-induced attenuation: GeE', Ge(1), Ge(2), and Ge-ODC. The generation mechanisms of Ge-ODC and charged defects like GeE' centers are studied through ab initio simulation. Our calculations used a 108 atom supercell with a glass composition comparable to the Ge-doped core or to the pure-silica cladding of the canonical sample. The large size of our cell allows us to study the influence of the local environment surrounding the X-ODC defect (X = Si or Ge) on its structure parameters (e.g., Si-X bond length) and its energy of formation. We found a statistical correlation between these two characteristics for pure- and Ge-doped silica-based glasses suggesting that the Si-ODC and Ge-ODC will be preferentially generated at sites leading to the shortest Si-X distances. We also evaluated the possible influence of the local environments of the defect on their generation mechanisms. From the whole set of possible X-ODC in the amorphous cells, we calculated the charged structures that can be obtained through the removing of one electron of the cell. For pure-silica glass, about 80% of the oxygen vacancies lead to a dimer structure and 20% to puckered ones. For the doped glass, the percentage of the final dimer structures is reduced to 42% while the puckered charged percentage increases to 36%. We also note the appearance of 22% of divalent centers. Further simulation shows that the presence of the Ge inside the glass strongly affects the generation mechanisms of Si-related centers. Index Terms--Ab initio calculations, defects, density functional theory, optical fibers, radiation effects, silica.

The production of secondary recoiled particles from interactions between high energy protons and microelectronics devices was investigated. By using NAND Flash memories, we were able to directly obtain analog information on recoil characteristics. While our results qualitatively confirm the role of nuclear reactions, in particular of those with tungsten, a quantitative model based on Monte Carlo and device-level simulations cannot describe the observed results in terms of recoils from proton-W reactions. Index Terms--Floating gate memories, high energy protons, single event effects, space radiation.

We characterized the responses of three erbium-doped fibers with slightly different concentrations of rare-earth ions (240-290 ppm) and [Al.sub.2][O.sub.3] (7-10 wt.%) during proton and [gamma]-ray exposures. We have simultaneously measured the radiation-induced attenuation (RIA) around the [Er.sup.3+] ion pumping wavelength (980 nm) and the associated changes of the [Er.sup.3+] emission around 1530 nm. The three erbium-doped fibers show similar radiation responses. All fibers exhibit RIA levels between 9 x [10.sup.-3] and 1.7 x [10.sup.-2] dB [m.sup.-1] [Gy.sup.-1] at 980 nm and between 4 x [10.sup.-3] and 1.1 x [10.sup.-2] dB [m.sup.-1] [Gy.sup.-1] at 1530 nm. Protons and [gamma]-rays lead to similar radiation damages, with small differences between the protons of different energies (50 MeV and 105 MeV). Furthermore, we have performed online measurements of the spectral dependence of RIA from 600 to 1600 nm and offline measurements from 1200 to 2400 nm. The three fibers exhibit the same spectral response. Losses decrease monotonically from the visible to the infrared part of the spectrum. We have performed spectral decomposition of these RIA curves with the help of absorption bands previously associated with radiation-induced point defects. Our analysis shows that the main part of the RIA (600-1700 nm) in erbium-doped glass can be explained by the generation of Al-related point defects. The other defects related to the germanium and phosphorus doping of the silica seem to have a lower contribution to the induced losses. The [Er.sup.3+] ion properties seem to be mainly unaffected by proton exposure, suggesting a solvation shell around the [Er.sup.3+] ion formed by [Al.sub.2][O.sub.3] species. Index Terms--Color centers, erbium, gamma, optical fibers, protons, radiation effects.

The generation and propagation of single event transients (SET) is measured and modeled in SOI inverter chains with different designs. SET propagation in inverter chains induces significant modifications of the transient width. In some cases, a 'propagation-induced pulse broadening' (PIPB) effect is observed. Initially narrow transients, less than 200 ps at the struck node, are progressively broadened up to the nanosecond range, with the degree of broadening dependent on the transistor design and the length of propagation. The chain design (transistor size and load) is shown to have a major impact on the transient width modification. Index Terms--Chains of inverters, digital single event transients, heavy ion and pulsed laser irradiation, propagation-induced pulse broadening (PIPB) effect, SET propagation, SET width.

The effects of heavy ion energy and nuclear interactions on the single-event upset (SEU) and single-event latchup (SEL) response of commercial and radiation-hardened CMOS ICs are explored. Above the threshold LET for direct ionization-induced upsets, little difference is observed in single-event upset and latchup cross sections measured using low versus high energy heavy ions. However, significant differences between low- and high-energy heavy ion test results are observed below the threshold LET for single-node direct ionization-induced upsets. The data suggest that secondary particles produced by nuclear interactions play a role in determining the SEU and SEL hardness of integrated circuits, especially at low LET. The role of nuclear interactions and implications for radiation hardness assurance and rate prediction are discussed. Index Terms--Indirect ionization, integrated circuit reliability, nuclear reactions, radiation effects, radiation hardness assurance, single-event effects, single-event latchup, single-event upset, soft errors.

The neutron-induced SEU sensitivity in the 1-10 MeV energy range is investigated using monoenergetic neutron beams at 2.5, 4, 6, and 14 MeV. Below the 0.25 [micro]m technology node, bulk technologies exhibit a relatively high sensitivity to neutrons between 4 and 6 MeV which is explained by the contribution of alpha particles coming from (n, [alpha]) reactions. In the terrestrial environment, the contribution to SER of neutrons in this energy range exceeds 10%. Index Terms--Neutron, SEU, SRAM, SOI.

We investigate the radiation-induced effects on pure-silica-core (PSC) optical fibers. For this, we measured the radiation-induced attenuation (RIA) growth and decay kinetics in four fibers with different hydroxyl and chorine contents. Our results show that PSC fibers exhibit different transient and continuous radiation responses depending of the silica-glass composition. Self-trapped charges [self-trapped excitons (STEs) and self-trapped holes (STHs)] seem mainly responsible for the fiber transient responses (times shorter than 1 s after the X-ray pulse) in the ultraviolet to near infrared part of the spectrum (300-900 nm). As these defects are unstable at room temperature, the contribution of other defects, like non-bridging oxygen hole centers (NBOHC) increases with time. Finally, these stable defects mainly explain the fiber permanent responses. To complete our online RIA measurements, we also studied by confocal microscopy luminescence (CML) the spatial distribution of the stable radiation-induced emitting centers in both pristine and irradiated fibers. Our CML results, obtained with 514 and 633 nm laser excitation, showed that several optically-active centers are non-uniformly generated in the fiber cross-sections. The generation of NBOHC by breakage of Si-O-Si strained bonds is clearly enhanced in high-OH fibers, especially at their core and cladding interfaces. The generation mechanisms of other unidentified defects emitting around 600 nm seem to be affected by both the hydroxyl content in the fiber core and by another factor that is not related to the silica glass composition. Index Terms--Color centers, confocal microscopy luminescence, [gamma]-rays, optical fibers, pulsed X-rays, radiation-induced effects.

The impact of quantum confinement effects on the transient response of 32 nm Multiple-Gate nanowire MOSFETs to heavy ion irradiation is investigated using 3D quantum numerical simulation. The drain current transient induced by an ion strike and the bipolar amplification of Double-Gate, Triple-Gate, Omega-Gate and Gate-All-Around architectures is simulated for the 2007, 2009 and 2011 ITRS Low Power technology nodes. The consequences of quantum-mechanical confinement on single-event transient immunity when devices are scaled down to 20 nm gate length and 5 nm thick silicon channel are then analyzed. Index Terms--Double-Gate (DG), Gate-All-Around (GAA), Multiple-Gate nanowire MOSFET, Omega-Gate ([OMEGA]-Gate), quantum-mechanical effects, 3D quantum simulation, Triple-Gate (Tri-gate).

The impact of heavy ion energy on SEU and SEL in commercial and radiation-hardened CMOS SRAMs is explored. Provided the ion range is large enough for the ions to reach the sensitive device region, standard low-energy heavy ion testing is conservative with respect to high-energy heavy ions, at least for LETs above the threshold for direct ionization-induced upsets. However, below the threshold LET for direct ionization-induced effects we find some differences between low- and high-energy tests. These differences are attributed to the effects of nuclear reaction-induced secondary particles. Implications for hardness assurance testing and error rate calculations are discussed. Index Terms--Indirect ionization, integrated circuit reliability, nuclear reactions, radiation effects, radiation hardness assurance, single event effects, single event latchup, single event upset.

In this paper, we investigate the mechanisms of absorbing defect generation by pulsed X-rays (~1 MeV), [gamma]-rays (~1.2 MeV) and 14-MeV neutrons in silica-based optical fibers. We measure the spectral and temporal dependence of the radiation-induced attenuation (RIA) from the ultraviolet to the near-infrared part of the spectrum (300-900 nm). The choice of the dopants incorporated in the fiber core and cladding strongly affects the fiber radiation tolerance. The structure and generation mechanisms of the point defects responsible for the fiber degradation are discussed on the basis of Gaussian decomposition of the RIA spectra with previously characterized absorption bands. In this spectral range, the absorption bands at 2.2, 2.5, and 3.1 eV (570, 510, and 400 nm) of phosphorus(P)-oxygen hole centers (POHC) explain the increase of losses in P-codoped fibers. For P-free fibers, our measurements showed that the RIA can be attributed to different germanium-related defects with absorption bands centered at 4.41, 2.61, and 1.97 eV (280, 475, and 630 nm) respectively, named Ge(1), GeX, and Ge-NBOHC centers. In the case of pulsed X-rays, another transient defect has been evidenced with an absorption band at 3.0 eV (400 nm, FWHM : 0.60 eV) that has been associated in the literature with the [[GeO4].sup.-] structure. Gamma-rays and 14-MeV neutrons globally lead to the same defect generation mechanisms and the same class of defects contributes to the induced losses. For a high dose rate environment and high-speed transmission measurements, very unstable defects, like self-trapped charges, have to be considered for the evaluation of the transient vulnerability of optical fibers. Index Terms-[gamma]-rays, neutrons, optical fibers, point defects, pulsed X-rays, radiation-induced effects.

The response to single-event transient of decananometer SOI MOSFETs is investigated by heavy ion experiment and by 3D quantum simulation. The 50 nm FD Single-Gate SOI devices have been irradiated with heavy ions at GANIL (Caen, France) using a new experimental setup. Three-dimensional numerical simulation is used to get further insights and to extrapolate the experimental results when devices are scaled down. For ultra-thin films new phenomena such as quantum-mechanical confinement have to be carefully considered in the device simulalion. These effects are found to have an increasing impact on the operation of future ultra-thin single- and double-gate devices submitted to heavy ion irradiation. Index Terms--Double-gate MOSFET, fully-depleted single-gate silicon-on-insulator (SOI) MOSFET, heavy-ion experiment, quantum-mechanical effects, 3D quantum simulation.

The statistical transient response of floating body SOI and bulk devices is measured under proton and heavy ion irradiation. The influence of the device architecture is analyzed in detail for several generations of technologies, from 0.25 [micro]m to 70 nm. The effects of the measured transients on SET sensitivity are investigated. The amount of collected charge and the shape of the transient currents are shown to have a significant impact on the temporal width of propagating transients. Finally, based on our measured data, the threshold LET and the critical transient width for unattenuated propagation are calculated for both bulk and floating body SOI as a function of technology scaling. We show that the threshold LETs and the critical transient widths for bulk and floating body SOI devices are similar. Body ties can be used to harden SOI ICs to digital SET. However, the primary advantage of SOI technologies, even with a floating body design, mostly lies in shorter transients, at a given ion LET, for SOI technologies than for bulk technologies. Index Terms--Collected charge, heavy ion and proton irradiation, single event transient, SOI and bulk transistors, statistical response, transient current, transient width.

The sensitivity to heavy ions of three 45-nm multi-gate transistors is evaluated by 3-D simulation. An in depth investigation of main internal parameters is performed to study the electrical response of the different device architectures under irradiation. The obtained results are in agreement with the electrical behavior trends of these devices. Index Terms--Bipolar gain, double-gate transistor, FinFET transistor, GAA transistor, MOSFET.

The effect of proton angle of incidence on proton-induced single-event latchup (SEL) is investigated in detail at room and elevated temperatures in present-day SRAMs. SRAMs from seven different vendors were irradiated at proton energies from 50 to 200 MeV, at temperatures of 25 [degrees]C and 75 [degrees]C, and at angles of incidence from 0[degrees] (normal) to 85[degrees] (grazing). The effects of angle of incidence were also investigated for neutron-induced SEL. The angle of incidence can significantly impact SEL hardness. For one SRAM at a temperature of 75 [degrees]C, characterizing SEL cross section at grazing angle resulted in a 16 times increase in SEL cross section. Large increases in SEL cross section with angle were also observed for other SRAMs characterized at room temperature. These increases in SEL cross section with angle of incidence are much larger than those measured previously for older SRAM technologies. The mechanism for the effect of angle of incidence on SEL cross section is not due simply to the deposition of more energy in the sensitive volume caused by an increase in path length as the angle of incidence is increased. To investigate possible mechanisms nuclear scattering calculations were performed and combined with device simulations. Simulation results suggest that the mechanism is a consequence of the linear energy transfer (LET) and range distributions of secondary ions produced by proton-material (or neutron-material) interactions coupled with an increase in SEL sensitivity (decrease in LET threshold) as angle of incidence is increased. These results have significant impact on SEL hardness assurance testing, especially for system applications where latchups cannot be tolerated. To best ensure that SEL hardness requirement are met, SRAMs should be characterized at both grazing and normal angles of incidence, and at maximum temperature, voltage, and proton energy. Index Terms--Hardness assurance, proton radiation effects, single-event effects, single-event latchup.

Three-dimensional (3-D) numerical simulations of decananometer Gate-All-Around transistors with 30 nm channel length and 10 um Silicon film thickness have been performed to deeply investigate their electrical response to heavy ions irradiation. Results show that these GAA devices exhibit an excellent control of both impact ionization and bipolar amplification. A careful comparison between two-dimensional (2-D) and 3-D simulations is also reported to explore the limits of the 2-D approach for such ultra-deep submicrometer multi-gate device architectures. Index Terms--Bipolar amplification, gate-all-around transistor, heavy ions, MOSFET, simulation.

This paper investigates the single event upset sensitivity of Bulk SRAMs for terrestrial applications. The technology sensitivity is analyzed with both quasi-monoenergetic neutron and proton experiments in an energy range from 14 to 180 MeV. Analytical and simulation based correction methods of the neutron cross section are presented and validated. Then, neutron and proton cross section are compared. Soft Error Rate (for the terrestrial neutron spectrum) calculated with either proton or quasi-monoenergetic neutron data are also presented and compared. Index Terms--Bulk technologies, neutron and proton effects, soft error rate (SER), single-event upset (SEU).

The effect of total dose on SEU hardness is investigated as a function of temperature and power supply voltage to determine worst-case hardness assurance test conditions for space environments. SRAMs from six different vendors were characterized for single-event upset (SEU) hardness at proton energies from 20 to 500 MeV and at temperatures of 25 and 80[degrees]C after total dose irradiating the SRAMs with either protons, Co-60 gamma rays, or low-energy x-rays. It is shown that total dose irradiation and the memory pattern written to the memory array during total dose irradiation and SEU characterization can substantially affect SEU hardness for some SRAMs. For one SRAM, the memory pattern made more than two orders of magnitude difference in SEU cross section at the highest total dose level examined. For all SRAMs investigated, the memory pattern that led to the largest increase in SEU cross section was the same memory pattern that led to the maximum increase in total-dose induced power supply leakage current. In addition, it is shown that increasing the temperature during SEU characterization can also increase the effect of total dose on SEU hardness. As a result, worst-case SEU hardness assurance test conditions are the maximum total dose and temperature of the system environment, and the minimum operating voltage of the SRAM. Possible screens for determining whether or not the SEU cross section of an SRAM will vary with total dose, based on the magnitude of the increase in power supply leakage current with total dose or the variation in SEU cross section with power supply voltage, have been suggested. In contrast to previous works, our results using selective area x-ray irradiations show that the source of the effect of total dose on SEU hardness is radiation-induced leakage currents in the memory cells. The increase in SEU cross section with total dose appears to be consistent with radiation-induced currents originating in the memory calls affecting the output bias levels of bias level shift circuitry used to control the voltage levels to the memory cells and/or due to the lowering of the noise margin of individual memory cells caused by radiation-induced leakage currents. Index Terms--Hardness assurance, proton irradiation, single-event upset.

We have investigated the variation of the optical absorption induced by pulsed (dose rate > [10.sup.8] rad/s) and continuous ( Index Terms--Color centers, optical fibers, pulsed X-rays, radiation-induced effects, [gamma]-rays.

Transient radiation-induced effects in air-guiding photonic crystal fibers (Air-PCF) are investigated for the first time to our knowledge. We characterize the vulnerability of this kind of waveguide by measuring the time dependent changes of their radiation-induced attenuation (RIA) at 1.55 [micro]m. We compare their radiation response to those of two silica-based single-mode fibers with germanium-doped and pure-silica cores. An X-ray pulse induces globally the same effects in all waveguides: a strong and transient increase of RIA. For higher tested doses (10 < D < 100 Gy), Air-PCF exhibits an interesting saturation of RIA at ~0.1 dB/m. The possible mechanisms involved in this radiation response are discussed. In particular, we assume that the design of the photonic bandgap structure of the fiber, responsible for the light guidance in the air-core, could strongly affect the amplitude of RIA. The kinetics of RIA recovery depends predominantly on the point defects created at the air/silica interface and in the silica-based part of the microstructured cladding. Index Terms--Color centers, photonic crystal fibers, pulsed X-rays, radiation effects.

The effect of proton energy on single-event latchup (SEL) in present-day SRAMs is investigated over a wide range of proton energies and temperature. SRAMs from five different vendors were irradiated at proton energies from 20 to 500 MeV and at temperatures of 25[degrees] and 85[degrees]C. For the SRAMs and radiation conditions examined in this work, proton energy SEL thresholds varied from as low as 20 MeV to as high as 490 MeV. To gain insight into the observed effects, the heavy-ion SEL linear energy transfer (LET) thresholds of the SRAMs were measured and compared to high-energy transport calculations of proton interactions with different materials. For some SRAMs that showed proton-induced SEE the heavy-ion SEL threshold LET was as high as 25 MeV-[cm.sup.2]/mg. Proton interactions with Si cannot generate nuclear recoils with LETs this large. Our nuclear scattering calculations suggest that the nuclear recoils are generated by proton interactions with tungsten. Tungsten plugs are commonly used in most high-density ICs fabricated today, including SRAMs. These results demonstrate that for system applications where latchups cannot be tolerated, SEL hardness assurance testing should be performed at a proton energy at least as high as the highest proton energy present in the system environment. Moreover, the best procedure to ensure that ICs will be latchup free in proton environments may be to use a heavy-ion source with LETs [greater than or equal to] 40 MeV-[cm.sup.2]/mg.

This paper investigates the sensitivity of SOI and Bulk SRAMs to neutron irradiations with energies from 14 to 500 MeV. The technology sensitivity is analyzed with both experiments and Monte Carlo simulations. In particular, simulations include the nuclear interactions of neutrons with both silicon and oxygen nuclei In-St and n-O), in order to investigate the influence of isolation upper layers on the device sensitivity. The device cross-sections are analyzed for mono-energetic neutron irradiations and discussed in terms of nuclear interaction type (n-St and n-O) and distribution of the secondary ion recoils. We also investigate the dimensions of the interaction volume around the sensitive cell as a function of the device architecture. Index Terms--Bulk technologies, SOI technologies, neutron effects, soft error rate (SER), single-event upset (SEU), Monte Carlo methods.

The SEU sensitivity of 0.2 [micro]m fully depleted silicon on ensulator (FD-SOI) devices to proton and neutron irradiations is investigated in a large energy range (14-500 MeV). The comparison to bulk devices with similar gate lengths shows an improvement of a factor of 50 with the presence of body ties. Monte Carlo simulations were performed to confirm that the low sensitivity of FD-SOI is mainly due to the reduced sensitive volume. These results were extrapolated to deca-nanometric technologies to predict the behavior of advanced SOI processes. We found that fully depleted devices will be far less sensitive than partially depleted technologies to the terrestrial radiative environment. Index Terms--Neutron, proton, SEU, SOI, SRAM.

The sensitivity to heavy ions of double-gate (DG) transistors is evaluated by numerical simulation and extensively compared with the response of single-gate (SG) partially-depleted and fully-depleted SOI devices. The study of bipolar amplification versus LET and track location shows that DG are less sensitive than SG with similar structure parameters. Moreover, in order to understand the downscaling impact on the DG sensitivity to heavy ions, the influence on the bipolar gain of various electrical and geometrical structure parameters is thoroughly analyzed. Index Terms--Bipolar gain, double-gate transistor, MOSFET, single-gate SOI transistor.

The Laser Megajoule project is a major component of the French simulation program to study nuclear fusion by inertial confinement. The future Laser Megajoule facility requires control-command systems that will operate in a harsh radiative environment. Commercial off-the-shelf optical fiber data links are envisaged as a radiation tolerant solution for this application. In this paper, we present our preliminary study of their vulnerability. For this, we firstly have used an original method consisting of ultraviolet (~ 5 eV) exposures of the fibers to identify the different germanosilicate optical fibers containing phosphorus, which leads them unacceptable for both steady state [gamma]-rays and successive pulsed X-ray irradiations. We have demonstrated the validity of the [gamma]-UV comparison by spectroscopic measurements. After this first selection, we have tested under pulsed X-rays (dose rate 10 MGy/s dose < 0.5 kGy) the resistance of the P-free optical fibers at 1310 nm for the shortest times after an ionization pulse ([10.sup.-9] to [10.sup.-1] s). Based on these results, we discuss the validity of the optical fiber data links for the control-command applications in LMJ facility. Index Terms--Color centers, gamma rays, optical fiber, pulsed X-ray irradiation, radiation effects, ultraviolet exposures.

The impact of total ionizing dose and displacement damage on single-event upset and single-event latchup hardness assurance testing of present-day commercial SRAMs is studied over a wide range of proton energies and fluence levels. Commercial SRAMs from six different vendors were irradiated at proton energies from 8 to 500 MeV and at total doses from 0 to 100 krad(Si) using multiple radiation sources. For some SRAMs, the single-event upset cross section increased with total dose. The amount of increase in SEU cross section strongly depended on the bias configuration during total dose irradiation and single-event upset characterization. For most of the SRAMs that showed an increase in single-event upset cross section with total dose, the static power supply leakage current also increased. Light emission microscopy photographs identified the source of the increase in power supply leakage current for these SRAMs as originating in peripheral transistors outside the memory array. This suggests a new single-event upset mechanism for present-day devices, which may be due to a reduction in the internally supplied memory array bias level with total dose, increasing memory cell sensitivity to single-event upset. The proton energy at which the single-event latchup cross section saturated varied considerably between devices. For one technology, the single-event latchup cross section did not saturate until the proton energy was increased to 200 MeV. These data indicate that single-event latchup hardness assurance testing should be performed at high proton energies (> 100 MeV). For fluence levels less than [10.sub.11] protons/[cm.sub.2] at a proton energy of 105 MeV, proton-induced displacement damage had no observable affect on single-event latchup cross section. The implications of these effects on single-event upset and latchup hardness assurance testing are discussed. Index Terms--Integrated circuit reliability, integrated circuit testing, proton testing, radiation effects, radiation hardening (electronics), radiation response, single event effects, single event latchup, single event upset.

This paper investigates the sensitivity of bulk technologies in the terrestrial neutron environment as a function of technology scaling. Their sensitivity is analyzed with both experiments and Monte Carlo simulations. The soft error rate (SER) of future technology generations is extrapolated, analyzed and discussed on the basis of different parameters such as the interaction volume, the secondary ion species and the incident neutron energy ranges. Index Terms--Bulk technologies, Monte Carlo methods, neutron effects, soft error rate, single-event upset, SRAM chips.

Results of WNR continuous spectrum irradiations are compared to mono-energetic proton and neutron data according to the JEDEC-JESD89 test procedure. A good correlation between these two methods is found particularly when 500 MeV proton cross-section is used instead of the one at 150 MeV. The increased contribution of the low energy part of the spectrum for modern devices is also discussed. Finally, the influence of front side and back side irradiations is studied at different energies and for several devices from 0.8 [micro]m to 0.18 [micro]m technologies. Index Terms--Bulk technologies, neuron effects, proton effects, soft error rate (SER), single-event upset (SEU).

This paper investigates the charge collection mechanisms occurring in heavy ion irradiated metal oxide semiconductor (MOS) devices. The parasitic bipolar effect, inherent to the structure of SOI transistors, is shown to exist in bulk NMOS transistors as well. We experimentally show that the drain junction of an OFF-state bulk MOS transistor collects more charge than an identical junction isolated from neighboring elements. In other words, the proximity of the source junction and the triggering of the bipolar-like structure are responsible of charge amplification. A higher current peak on the drain is observed, and this enhancement effect is high enough to invalidate usual charge collection models based only on funnel and diffusion transport. Thus, the proximity of other junctions has to be considered to improve charge collection model in bulk technologies. Index Terms--Bipolar amplification, bulk and SOI transistors, charge collection, heavy ion irradiation, transport by funnelling and diffusion.

This paper analyzes the collected charge in heavy ion irradiated MOS structures. The charge generated in the substrate induces a displacement effect which strongly depends on the capacitor structure. Networks of capacitors are particularly sensitive to charge sharing effects. This has important implications for the reliability of SOI and DRAMs which use isolation oxides as a key elementary structure. The buried oxide of presentday and future SOI technologies is thick enough to avoid a significant collection from displacement effects. On the other hand, the retention capacitors of trench DRAMs are particularly sensitive to charge release in the substrate. Charge collection on retention capacitors participate to the MBU sensitivity of DRAM. Index Terms--Capacitors, charge collection, charge sharing, device simulation, diodes, DRAMs, heavy ion irradiation, isolation oxides, MBU sensitivity, MOS structures, SOI technology, SRAMs, transient currents, trench capacitors.

This work investigates the effects of 14-MeV neutron irradiation on bulk and silicon-on-insulator (SOI) technologies. Experimental results are reported with a study on the influence of the irradiation angle. These experiments are interpreted with a nuclear interaction code (MCNP: Monte Carlo N-Particle). The device architecture and the involved materials are shown to be determining parameters with respect to the device sensitivity. Index Terms--Alpha particle, bulk SRAM, elastic, inelastic, irradiation angle, linear energy transfer, Monte Carlo simulation, neutron cross-section, neutron irradiation, nonelastic, semiconductor reliability, single event upset, SOI SRAM, terrestrial environment.

Radiation hardness of LiNb[O.sub.3] : Ti Mach-Zehnder optomodulators under high energy electron pulses at high dose rate is studied for the first time. Both electrical and optical measurements are performed at various dose rates and electrical bias conditions. Electrical and optical perturbations are observed to be synchronous of the irradiation pulse, below a total dose threshold of 1 krad(Si). The optical behavior of the various optomodulators under test is related to their structure. As a matter of fact, optical perturbations are due either to photocurrent which superposes to electrical bias, or to an alteration of couplers characteristics.

We have studied the electrical and optical response of two laser diodes under transient irradiation. Both diodes exhibit a positive photocurrent, which adds to the bias current, and a decrease of the optical power until extinction when dose rate is increased. Direct carder generation in the laser cavity is a second order phenomena. The diode overall response is driven by both the substrate photocurrent and the transient conduction of current confinement regions, which decrease the net current density in the cavity and switches-off the laser emission. This behaviour is in good agreement with pulsed electrical characterizations and 2D simulations.

We have studied transient irradiation effects on the optical and electrical responses of a laser diode. The influence of dose rate, ranging from [10.sup.9] to [10.sup.12] rad(Si)/s, has been investigated through a complete experimental study. Dose rate vulnerability of the laser diode has been observed. Electrical and optical transient responses are determined by the dose rate, the diode structure, and its operating point.