Displacement Damage Effects Research Articles

Hardening of a radiation sensor based on optically stimulated luminescence

The loss of sensitivity induced by the displacement damage effect on the optically stimulated luminescent dosimeter is investigated. A new architecture is proposed and successfully tested to harden the sensor at system level.

SPICE modeling of neutron displacement damage and annealing effects in bipolar junction transistors

For the purpose of simulating the effects of neutron radiation damage on bipolar circuit performance, we have developed a bipolar junction transistor SPICE model that incorporates displacement damage effects. A physics-based formalism is used for describing the radiation effects within the framework of the Gummel-Poon model. A model structure that includes the dependence of neutron fluence on the relevant SPICE parameters is outlined, from which a simplified radiation model is established. The latter is presented and implemented in AIM-Spice, and it is shown to agree quite well with experiments. Dynamic effects including annealing are also discussed.

Synergistic Effect of Displacement Damage, Helium and Hydrogen of Silicon Carbide Composite

ABSTRACTThe mechanical properties of advanced SiC/SiC composite and polycrystalline, monolithic β-SiC under dual- and triple-ions irradiation to 1 and 10 dpa at 800°C, 1000°C, and 1300°C were investigated by a Nano-indentation test. Preliminary microstructural analysis by transmission electron microscopy was performed. Hardness and elastic modulus changes in response to ion irradiation were observed, but synergistic effects on these mechanical properties were not significant. In contrast, microstructural observation of the composites after 10 dpa at 1000°C showed that cavity formation behavior was dependent on the material and the helium or hydrogen implanted mode. The effect of gas elements on cavity formation and the mechanical properties are discussed.

Review of displacement damage effects in silicon devices

This paper provides a historical review of the literature on the effects of radiation-induced displacement damage in semiconductor materials and devices. Emphasis is placed on effects in technologically important bulk silicon and silicon devices. The primary goals are to provide a guide to displacement damage literature, to offer critical comments regarding that literature in an attempt to identify key findings, to describe how the understanding of displacement damage mechanisms and effects has evolved, and to note current trends. Selected tutorial elements are included as an aid to presenting the review information more clearly and to provide a frame of reference for the terminology used. The primary approach employed is to present information qualitatively while leaving quantitative details to the cited references. A bibliography of key displacement-damage information sources is also provided.

Swelling behavior of F82H steel irradiated by triple/dual ion beams

Irradiations for spallation target vessels and structural materials of fusion reactors were simulated using simultaneous triple/dual ion beams consisting of Fe 3+, He + and H + ions or Fe 3+ and He + ions at temperatures between 470 and 600 °C to 50 dpa. The swelling of F82H (Fe–8Cr–2W–0.2V–0.04Ta–0.1C) martensitic steel was enhanced by a synergistic effect of displacement damage and the implantation of helium and hydrogen. The maximum swelling of F82H steel was 3.2% at 470 °C under a simulation of structural materials of fusion reactors, and was higher than 1.2%, which applied to a simulation of spallation target vessel. The swelling under a simulation of fusion reactor decreased with increasing irradiation temperature, however the swelling under a simulation of spallation target vessel was again increased at 600 °C by the high helium concentration. From the microstructural analysis of taking account of cavity growth process, the cause of the enhancement of swelling under a simulation of fusion reactor is thought to be gas pressure of hydrogen and helium in cavities during irradiation. The effects of 50% cold-working and carbon implantation on swelling behavior were also examined. The swelling was reduced from 3.2% to 1.4% by 50% cold-working, and to 0.5% by carbon implantation.

RADIATION EFFECTS IN III-V SEMICONDUCTOR ELECTRONICS

Particle irradiation effects in III-V semiconductor devices and selected circuits are reviewed. Radiation effects concerns in III-V devices are associated primarily with displacement damage and single-event upset. In conventional transistors, displacement damage decreases the gain, increases leakage and shifts the collector-emitter offset voltage. In reduced dimensional devices. such as high electron mobility transistors and resonant tunneling diodes, the main displacement damage effect is to reduce current by increasing scattering out of the two-dimensional transport state. The current understanding of single-event effects in III-V circuits and devices, and approaches for mitigating their impact, are also discussed here. Single-event effects are a serious concern for high-speed III-V semiconductor devices operating in radiation-intense environments. GaAs integrated circuits (ICs) based on field effect transistor technology exhibit single-event upset sensitivity to protons and very low linear energy transfer (LET) particles; this sensitivity becomes more significant as clock rates and operating speeds increase.

Total Ionizing Dose and Displacement-Damage Effects in Microelectronics

AbstractWhen exposed to radiation, the function of microelectronic devices is not only degraded by single-event phenomena but by cumulative effects. Most of the energy lost by radiation passing through semiconductors is through ionization. Buildup of charge in gate oxide layers and of interface and border traps due to ionization result in semipermanent damage to the device. These effects are known as total ionizing dose effects. A fraction of the energy of the radiation passing through semiconductors is lost to displacement of atoms from their sites in the crystal lattice structure. The buildup of displacement damage with radiation exposure causes gradual but permanent changes in device performance and limits device lifetime in a radiation environment. Displacement damage will be discussed in the context of non-ionizing energy loss.

Total dose and displacement damage effects in a radiation-hardened CMOS APS

A 512/spl times/512 CMOS active pixel sensor (APS) was designed and fabricated in a standard 0.5-/spl mu/m technology. The radiation tolerance of the sensor has been evaluated with Co-60 and proton irradiation with proton energies ranging from 11.7 to 59 MeV. The most pronounced radiation effect is the increase of the dark current. However, the total ionizing dose-induced dark current increase is orders of magnitude smaller than in standard devices. It behaves logarithmically with dose and anneals at room temperature. The dark current increase due to proton displacement damage is explained in terms of the nonionizing energy loss of the protons. The fixed pattern noise does not increase with total ionizing dose. Responsivity changes are observed after Co-60 and proton irradiation, but a definitive cause has not yet been established.

Separation of ionization and displacement damage using gate-controlled lateral PNP bipolar transistors

Proton irradiation produces both ionization and displacement damage in semiconductor devices. In this paper, a technique for separating the effects of these two types of damage using a lateral PNP bipolar transistor with a gate contact over the active base region is described. By biasing the gate appropriately, the effects of ionization-induced damage are minimized and the effects of displacement damage can be measured independently. Experiments and simulations are used to validate this approach and provide insight into proton-induced BJT degradation.

Analytical model for proton radiation effects in bipolar devices

The input bias current response of LM124 operational amplifiers to proton irradiation is shown to correlate with the response of identical part types exposed to neutrons and, subsequently, irradiated with X-rays. Moreover, the bias current responses to proton and combined neutron/X-ray exposures are more sublinear than the sum of neutron and X-ray radiation responses measured independently. These data indicate that the ionization defects introduced by proton irradiation moderate the effects of proton-induced displacement damage in the critical bipolar transistors within the LM124. An analytical model is presented that characterizes the various mechanisms of proton radiation effects in bipolar transistors, including the combined effects of oxide charge and bulk traps on carrier recombination. Prototype transistor responses simulated using the model show good correlation with the sublinear characteristics observed in the experimental data. Furthermore, the model is used to assess whether a bipolar junction transistor (BJT), designed with specific structural characteristics and operating in a proton-rich environment, will suffer the most degradation from damage caused by bulk displacement, ionization damage, or a combination of both.

Microstructural study of irradiated isotopically tailored F82H steel

The synergistic effect of displacement damage and hydrogen or helium atoms on microstructures in F82H steel irradiated at 250–400 °C to 2.8–51 dpa in HFIR has been examined using isotopes of 54 Fe or 10 B . Hydrogen atoms increased slightly the formation of dislocation loops and changed the Burgers vector for some parts of dislocation loops, and they also affected on the formation of cavity at 250 °C to 2.8 dpa. Helium atoms also influenced them at around 300 °C, and the effect of helium atoms was enhanced at 400 °C. Furthermore, the relations between microstructures and radiation-hardening or ductile to brittle transition temperature (DBTT) shift in F82H steel were discussed. The cause of the shift increase of DBTT is thought to be due to the hardening of dislocation loops and the formation of α ′-precipitates on dislocation loops.

Effect of triple ion beams in ferritic/martensitic steel on swelling behavior

The synergistic effects of displacement damage and atomic hydrogen and helium on swelling of the ferritic/martensitic steel, F82H, has been investigated. The irradiation was performed at temperatures between 470 and 600 °C to 50 dpa (displacement per atoms) under conditions of simultaneous ion beams consisting of Fe 3+, He + and H + ions or Fe 3+ and He + ions. The swelling of F82H steel under triple beams with 18 appm He/dpa and 70 appm H/dpa was larger than that under dual beams with 18 appm He/dpa. The swelling in F82H under triple beams increased with decreasing irradiation temperature from 0.1% to 3.2%, while swelling under dual beams was between 0.04% and 0.08%. On the other hand, in the case of triple beam irradiation with a high ratio of gas/dpa, the swelling tended to increase with irradiation temperature. The swelling in ferritic/martensitic steels is significantly enhanced by the synergistic effect of displacement damage, hydrogen and helium atoms.

Trends in optocoupler radiation degradation

Proton-radiation test results for new optocoupler technologies are compared with those of older optocouplers. The new devices are far more resistant to displacement damage effects and have a much higher current-transfer ratio (CTR). The improvements are due to improved optical-coupling efficiency in combination with light-emitting diode (LED) technologies that are inherently more resistant to lifetime degradation. Because of these changes, CTR degradation is no longer dominated by LED damage. LED degradation, gain degradation, and photoresponse degradation all contribute to the overall changes in CTR after irradiation in the newer device types.

Energy dependence of proton damage in optical emitters

The energy dependence of proton displacement damage effects is investigated for light-emitting diodes (LEDs) and laser diodes. Injection-enhanced annealing occurs more rapidly when devices are irradiated with protons below 50 MeV compared with annealing from 200-MeV protons. A different interpretation of damage in amphoterically doped LEDs is used to show that the dependence of damage on energy is relatively flat for energies above 50 MeV, in contrast to older results in the literature that show a continued decrease in damage at higher energies.

Low Temperature Swelling in Beta-SiC Associated with Point Defect Accumulation

An experimental technique to characterize irradiation-induced swelling, or isotropic volume expansion, through a combined utilization of medium-to-high energy accelerators and interferometric surface profilometry, was established. The technique was successfully applied to a characterization of swelling behavior in beta-silicon carbide arising from the accumulation of point defects at relatively low temperatures, i.e., 333–873 K, as a function of fluence level, displacement damage rate and irradiation temperature. Swelling rate and swelling at any given fluence level exhibited a negative dependence on irradiation temperature. The saturated low temperature swelling fell on the lower edge of neutron irradiated swelling data band. The influence of displacement damage rate appeared unremarkable. An additional study on the synergistic effect of atomic displacement damage and helium production revealed an enhancement of low temperature swelling in silicon carbide in the presence of helium.

Proton radiation response mechanisms in bipolar analog circuits

The experimental data presented in this paper indicate that the doping and geometry of critical transistors are the primary factors that affect the proton responses of the LM124 and LM148 operational amplifiers. The data also reveal that the electrical responses of these circuits and their input transistors to the combined effects of displacement damage and defects introduced by ionizing radiation are nonlinear. Analysis, supported by device simulation, shows that shifts in device parameters (surface potentials, carrier concentrations, etc.) caused by the buildup of oxide and interfacial defects affect the recombination rate due to traps resulting from displacement damage in the bulk silicon. This nonlinearity complicates the analysis of proton radiation effects and can have a significant impact on the qualification of analog parts for use in space environments.

Radiation damage in flash memory cells

Results are presented of a study on the effects of total ionization dose and displacement damage, induced by high-energy electrons, protons and alphas, on the performance degradation of flash memory cells integrated in a microcomputer. A conventional stacked-gate n-channel flash memory cell using a 0.8 μm n-polysilicon gate technology is employed. Irradiations by 1-MeV electrons and 20-MeV protons and alpha particles were done at room temperature. The impact of the fluence on the input characteristics, threshold voltage shift and drain and gate leakage was investigated. The threshold voltage change for proton and alpha irradiations is about three orders of magnitude larger than that for electrons. The performance degradation is mainly caused by the total ionization dose (TID) damage in the tunnel oxide and in the interpoly dielectric layer and by the creation of interface traps at the Si–SiO 2 interface. The impact of the irradiation temperature on the device degradation was studied for electrons and gammas, pointing out that irradiation at room temperature is mostly the worst case. Finally, attention is given to the impact of isochronal and isothermal annealing on the recovery of the degradation introduced after room temperature proton and electron irradiation.

Proton displacement damage in light-emitting and laser diodes

The effects of proton displacement damage on light-emitting diodes (LEDs) and laser diodes are discussed, comparing the radiation sensitivity of current technology devices with older devices for which data exist in the literature. Injection-enhanced annealing is discussed, along with the issue of energy dependence of proton displacement damage. New characterization methods are proposed for light-emitting diodes that complement measurement of light output and provide a better indication of nonradiative recombination centers.

Origin of hardening and deformation mechanisms in irradiated 316 LN austenitic stainless steel

The effects of displacement damage and trapped helium on deformation microstructures in AISI 316 LN austenitic stainless steel were studied by applying a newly developed disk bend method to specimens irradiated with 360 keV He ions at 200°C. Radiation damage microstructures consisted of an intimate mix of black dots, dislocation loops, and very small helium filled cavities. In the unirradiated specimens, the deformation mode upon straining was planar glide with cross-slip. With increasing dose, cross-slip was progressively restricted. Correspondingly, deformation microstructure changed from dislocation network dominant to channeling dominant. The channel bands were composed of piled-up dislocations, stacking faults, and twinned layers.

Proton irradiation of InAs/AlSb/GaSb resonant interband tunneling diodes

Room temperature current–voltage measurements have been made on InAs/AlSb/GaSb resonant interband tunnel diodes irradiated with 2 MeV protons to determine the effect of displacement damage on the negative resistance peak current Ip and the peak-to-valley current ratio P/V. Diodes with 5 and 13 ML AlSb barrier thickness were irradiated and measured several times until the total fluences reached 1×1015 and 2×1014 H+/cm2, respectively. The current due to radiation-induced defects has a nonlinear voltage dependence, with a large increase occurring in the voltage range between the negative resistance peak and the valley. Ip increased <50% while a large increase in the valley current decreased the P/V ratios to about 2.