Radiation-induced Leakage Research Articles

Chaperone- and PTM-mediated activation of IRF1 tames radiation-induced cell death and the inflammatory response.

The key role of structural cells in immune modulation has been revealed with the advent of single-cell multiomics, but the underlying mechanism remains poorly understood. Here, we revealed that the transcriptional activation of interferon regulatory factor 1 (IRF1) in response to ionizing radiation, cytotoxic chemicals and SARS-CoV-2 viral infection determines the fate of structural cells and regulates communication between structural and immune cells. Radiation-induced leakage of mtDNA initiates the nuclear translocation of IRF1, enabling it to regulate the transcription of inflammation- and cell death-related genes. Novel posttranslational modification (PTM) sites in the nuclear localization sequence (NLS) of IRF1 were identified. Functional analysis revealed that mutation of the acetylation site and the phosphorylation sites in the NLS blocked the transcriptional activation of IRF1 and reduced cell death in response to ionizing radiation. Mechanistically, reciprocal regulation between the single-stranded DNA sensors SSBP1 and IRF1, which restrains radiation-induced and STING/p300-mediated PTMs of IRF1, was revealed. In addition, genetic deletion or pharmacological inhibition of IRF1 tempered radiation-induced inflammatory cell death, and radiation mitigators also suppressed SARS-CoV-2 NSP-10-mediated activation of IRF1. Thus, we revealed a novel cytoplasm-oriented mechanism of IRF1 activation in structural cells that promotes inflammation and highlighted the potential effectiveness of IRF1 inhibitors against immune disorders.

Inhibiting astrocyte connexin-43 hemichannels blocks radiation-induced vesicular VEGF-A release and blood-brain barrier dysfunction.

Therapeutic brain irradiation with ionizing radiation exerts multiple side effects including barrier leakage that disturbs glial-neuronal functioning and may affect cognition. Astrocytes contribute to barrier leakage by endfeet release of various vasoactive substances acting on capillary endothelial cells forming the barrier. Here, we investigated X-ray effects on astrocytic vesicular transport in mice and determined whether interfering with astrocyte connexins affects radiation-induced barrier leakage. We found that astrocytic VEGF-A-loaded VAMP3 vesicles drastically reorganize starting from 6 h post-irradiation and move in a calcium- and Cx43-dependent manner towards endfeet where VEGF-A is released, provoking barrier leakage. Vesicular transport activation, VEGF-A release and leakage 24 h post-irradiation were all potently inhibited by astrocytic Cx43 KO, Cx43S255/262/279/282A (MK4) mutant mice and TATGap19 inhibition of Cx43 hemichannel opening. Astrocyte VEGF release is a major player in complications of brain irradiation, which can be mitigated by anti-VEGF treatments. Targeting Cx43 hemichannels allows to prevent astrocyte VEGF release at an early stage after brain irradiation.

Characterisation of gamma-irradiated MCz-silicon detectors with a high-K negative oxide as field insulator

Abstract The high-luminosity operation of the Tracker in the Compact Muon Solenid (CMS) detector at the Large Hadron Collider (LHC) experiment calls for the development of silicon-based sensors. This involves implementation of AC-coupling to micro-scale pixel sensor areas to provide enhanced isolation of radiation-induced leakage currents. The motivation of this study is the development of AC-pixel sensors with negative oxides (such as aluminium oxide — Al2O3 and hafnium oxide — HfO2) as field insulators that possess good dielectric strength and provide radiation hardness. Thin films of Al2O3 and HfO2 grown by atomic layer deposition (ALD) method were used as dielectrics for capacitive coupling. A comparison study based on dielectric material used in MOS capacitors indicate HfO2 as a better candidate since it provides higher sensitivity (where, the term sensitivity is defined as the ratio of the change in flat-band voltage to dose) to negative charge accumulation with gamma irradiation. Further, space charge sign inversion was observed for sensors processed on high resistivity p-type Magnetic Czochralski silicon (MCz-Si) substrates that were irradiated with gamma rays up to a dose of 1 MGy. The inter-pixel resistance values of heavily gamma irradiated AC-coupled pixel sensors suggest that high-K negative oxides as field insulators provide a good electrical isolation between the pixels.

Abstract 15392: Radiation-Induced Coronary Microvascular Leakage is Mediated by Loss of Endothelial Tight Junction Protein Claudin-1

Background: Ionizing radiation (IR) exposure to the heart during cancer therapy induces coronary microvascular leakage. Increased microvascular porosity allows inflammatory cell extravasation into the perivascular and myocardial interstitial space leading to fibrotic end organ damage. Hypothesis: Radiation-induced coronary microvascular leakage is mediated by a loss of a constitutively expressed tight-junction protein, claudin-1 (cldn1). Methods: We studied the function of cldn1 in human coronary vascular endothelial cells (HMVECs) and in mice using oligonucleotide-based cldn1 gene deletion. For the gain of function, we developed vascular-specific (VE-cadherin promotor-linked) claudin-1 overexpressing transgenic (TG) mice. We studied the effect of IR in cldn1 loss and gain of function models. Capillary permeability was assessed by FITC-dextran permeability and Evans blue dye injection, in vitro and in vivo, respectively . The extent of end-organ damage was examined by analyzing myocardial and perivascular fibrosis. Results: In HMVECs, cldn1 gene silencing (control, 1.0±0.34; siRNA, 0.026±0.03; p<0.001) led to increased permeability (control, 1.0±0.01, siRNA, 1.3±0.01; p<001). In mice, genetically engineered anti-cldn1 siRNA administration knocked down myocardial cldn1 expression (control, 1.0±0.18; siRNA, 0.51±0.11; p=0.04). Functionally, cldn1 knockdown led to increased microvascular extravasation (control, 1.0±0.23, cldn1-siRNA 0.38±0.27 p=0.002). Cardiac morphometry in these mice showed myocardial fibrosis (control, 1.0±0.19; siRNA, 1.29±0.35; p=0.048). Cardiac irradiation significantly decreased myocardial cldn1 (control 1.0±0.27, IR 0.45±0.31; p=0.001) and dye leakage (control 1.0±0.18, IR 1.28±0.22; p=0.007). Conversely, endothelium-targeted cldn1 overexpression in mice prevented abnormal microvasculature permeability (WT 1.0±0.23, TG 0.38±0.27 p=0.002) and conferred protection from IR-induced fibroinflammatory changes. Conclusions: Our study shows that cldn1 is crucial for maintaining coronary microvascular permeability. Prevention of cldn1 degradation or cldn1 reconstitution using novel pharmacotherapeutic approaches can prevent cardiac end-organ damage induced by cardiac IR.

Influence of Drain Bias and Flux on Heavy Ion-Induced Leakage Currents in SiC Power MOSFETs

Radiation-induced leakage current degradations for SiC power MOSFETs are investigated by <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">181</sup> Ta ion irradiation. An ion flux-related leakage degradation is reported for the first time. It is manifested as a more significant leakage current under higher flux irradiation than that under low flux irradiation, even though the total fluence is the same. Emission microscope (EMMI) results show that more leakage paths are formed for high flux irradiation. The drain bias during irradiation is another key fact to affect the radiation-induced leakage degradation. The leakage only occurs when the drain bias is larger than 300 V for flux = 1000/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}\cdot \text{s}$ </tex-math></inline-formula> irradiation. An interesting phenomenon is that although radiation-induced leakage is not observed at 200 V with ion flux of 1000/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}\cdot \text{s}$ </tex-math></inline-formula> , leakage appears when the ion flux increases to 6000/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}\cdot \text{s}$ </tex-math></inline-formula> . A multi-ion interaction theory is proposed to explain the above phenomenon. The mechanisms of these phenomena are also proved by TCAD simulations.

Negative-Bias-Stress and Total-Ionizing-Dose Effects in Deeply Scaled Ge-GAA Nanowire pFETs

Negative-bias-stress and total-ionizing-dose (TID) effects in deeply scaled Ge-gate-all-around (GAA) nanowire (NW) devices are characterized for different biasing conditions. Negative-bias-stress-induced degradation in Ge GAA device originates primarily from the interface- and border-trap generation. Devices stressed at high gate voltage show rapid initial degradation and quick saturation dominated by interface-trap generation. Radiation-induced OFF-state leakage current in Ge GAA NWs increases with dose due to enhanced band-to-band tunneling (BTBT) caused by charge trapping in the shallow trench isolation (STI).

Total Ionizing Dose Radiation Effects Hardening Using Back-Gate Bias in Double-SOI Structure

To mitigate the total ionizing dose (TID) radiation impact, a new structure named double-silicon-on-insulator (DSOI) is introduced in this article. This new structure exhibits potential benefits of reducing the radiation-induced degradation effectively and independently, thanks to the additional electrode, which can be used to control the internal electrical field of the device. With this structure, the TID response and TID mitigation strategy using back-bias are discussed in DSOI nMOSFETs. Then, a 3-D TCAD simulation model is proposed to analyze the radiation-induced leakage path for each bias configuration. The impact of negative back-bias during irradiation on trapped charge distribution is given for both buried oxide layer and shallow trench isolation. At last, a 4k-bit static random access memory is used to verify the effectiveness of back-bias on TID-induced leakage current suppression at the circuit level. The experimental results show the possibility of using back-bias against TID threat.

A Novel S-Gate-Assisted SOI n-MOSFET for Total Ionizing Dose Radiation Reinforcement

In this article, a novel S-gate-assisted silicon-on-insulator n-channel metal–oxide–semiconductor field-effect transistor (SGA SOI n-MOSFET) structure is proposed in order to suppress the total ionizing dose (TID) effect. The new structure settles the radiation-induced leakage current by isolating both the source and drain from the shallow trench isolation (STI) oxides and introducing two auxiliary gates. This work simulates the TID irradiation of three SOI n-MOSFET devices by Sentaurus TCAD and verifies the anti-TID irradiation characteristics of the proposed SGA SOI n-MOSFET. After the novel SGA SOI n-MOSFET was irradiated with 500 krad(Si), the OFF-state leakage current is only marginally increased, the ON-state leakage current is almost unchanged, the threshold voltage drift is 9.423%, and the transconductance degradation is only 7.453%. The simulation results demonstrated the proposed SGA SOI n-MOSFET resisted TID radiation doses up to 500 krad(Si). Meanwhile, the SGA SOI n-MOSFET is much more compact and saves tremendous cost compared with the H-gate-assisted (HGA) SOI n-MOSFET during very large scale integration (VLSI) fabrication and mass production. Moreover, the SGA SOI n-MOSFET solves the disadvantages of the ring-gate-assisted (RGA) SOI n-MOSFET complex aspect ratio <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}/{L}$ </tex-math></inline-formula> design. The SGA SOI n-MOSFET offers a better alternative for nonultrahigh radiation dose environments.

Characterization of Heavily Irradiated Dielectrics for Pixel Sensors Coupling Insulator Applications

An increase in the radiation levels during the high-luminosity operation of the Large Hadron Collider calls for the development of silicon-based pixel detectors that are used for particle tracking and vertex reconstruction. Unlike the conventionally used conductively coupled (DC-coupled) detectors that are prone to an increment in leakage currents due to radiation, capacitively coupled (AC-coupled) detectors are anticipated to be in operation in future collider experiments suitable for tracking purposes. The implementation of AC-coupling to micro-scale pixel sensor areas enables one to provide an enhanced isolation of radiation-induced leakage currents. The motivation of this study is the development of new generation capacitively coupled (AC-coupled) pixel sensors with coupling insulators having good dielectric strength and radiation hardness simultaneously. The AC-coupling insulator thin films were aluminum oxide (Al2O3) and hafnium oxide (HfO2) grown by the atomic layer deposition (ALD) method. A comparison study was performed based on the dielectric material used in MOS, MOSFET, and AC-coupled pixel prototypes processed on high resistivity p-type Magnetic Czochralski silicon (MCz-Si) substrates. Post-irradiation studies with 10 MeV protons up to a fluence of 1015 protons/cm2 suggest HfO2 to be a better candidate as it provides higher sensitivity with negative charge accumulation on irradiation. Furthermore, even though the nature of the dielectric does not affect the electric field within the AC-coupled pixel sensor, samples with HfO2 are comparatively less susceptible to undergo an early breakdown due to irradiation. Edge-transient current technique (e-TCT) measurements show a prominent double-junction effect as expected in heavily irradiated p-type detectors, in accordance with the simulation studies.

Abstract 11758: Prevention of Radiation-Induced Coronary Microvascular Leakage by the Restoration of an Endothelial Tight-Junction Protein

Introduction: In cancer survivors exposed to ionizing radiation (IR) exposure to the chest and heart, coronary endothelial injury and disruption of vascular barrier integrity is noted. The mechanisms driving the IR-induced leakiness of the coronary microvasculature are not known. There is no therapy to prevent such injury. Hypothesis: IR exposure downregulates a tight junction protein claudin-1 (cldn1), which can lead to altered endothelial barrier integrity. Ac-SDKP, an endogenous peptide, prevents cldn1 loss and preserves coronary vascular barrier function. Methods: We tested the constitutive and physiological effects of cldn1 both in vitro and in vivo . Human coronary vascular endothelial cells (HMVECs) lacking cldn1 by siRNA silencing were used for loss-of-function studies. Newly developed vascular-specific (VE-cadherin promotor-linked) cldn1 overexpressing transgenic (TG) mice were used for cldn1 gain-of-function studies. Mice were exposed to 45Gy chest radiation in fractionated doses (3Gy/day). A subgroup of irradiated mice was treated with Ac-SDKP (3.2mg/kg/day) for 3-weeks. Evans blue dye was injected via tail-vein 30 mins before euthanasia and dye extravasation through coronary microvasculature was quantified. Cldn1 expression was examined by Western blot and in vitro cell permeability was examined by FITC-dextran permeability assays. Results: Cldn1 silencing with siRNA showed increased permeability in HMVECs (control, 1.0±0.01, siRNA, 1.3±0.01; p=0.0002). Cardiac irradiation significantly decreased myocardial cldn1 (control 1.0±0.27, IR 0.45±0.31; p=0.001). Consequently, there was a significant increase in myocardial Evans blue dye extravasation compared to controls (control 1.0±0.22, IR 1.3±0.23, p=0.039). Cldn1 overexpression mice had decreased dye extravasation compared to WT controls (WT 1.0±0.23, TG 0.38±0.27 p=0.002). Ac-SDKP restored cldn1 protein expression, and inhibited dye leakage in the myocardium after IR exposure (0.57±0.21, p=0.048 vs IR). Conclusions: Our study shows that IR exposure induces endothelial barrier disruption through a reduced expression of endothelial tight-junction protein, cldn1. Ac-SDKP prevents these effects, at least in part, by preventing loss of claudin-1.

L Style n-MOSFET Layout For Mitigating TID Effects

This paper proposes a new rad hard layout L style of nmos metal oxide semiconductor field effect transistor (n-MOSFET), which is evaluated to show that its efficacy at reducing radiation-induced leakage currents, thus improving the total ionization dose(TID) tolerance with very less area and parasitic capacitance as compared to enclosed layout transistor(ELT). This proposed layout structure is fully compatible to present commercial fabrication technology without any additional mask requirement as compared to conventional n MOSFET fabrication and can be used as radiation tolerant by design technique. The simulated ID - VG characteristics of the rad hard L n-MOSFET layout demonstrated the effectiveness of eliminating radiation-induced leakage current paths. The leakage current in proposed rad hard L n-MOSFET has been reduced by factor of 108 at 300Krad dose as compared to conventional layout n-MOSFET.

Impact of Program/Erase Cycles, Total Ionizing Dose and Data Bake on Data Retention of 55nm SONOS Flash

In this paper, the data retention capability of 55nm SONOS Flash under the worst condition is studied by superimposing experiments of program/erase cycles, total ionizing dose (TID) and data bake. The results show that after 100k program/erase cycles and data bake, the data retention of the memory transistor is basically not affected. After 100k program/erase cycles, 200Krad(Si) TID and data bake, the data retention of the SONOS memory transistor is mainly reflected in the radiation-induced charge leakage. If the data is rewritten after TID, irradiation has basically no impact on its data retention capability.

Total-Ionizing-Dose Radiation-Induced Dual-Channel Leakage Current at Unclosed Edge Termination for High Voltage SOI LDMOS

Total-ionizing-dose (TID) radiation response on unclosed edge termination is investigated for high voltage silicon-on-insulator (SOI) laterally diffused metal-oxide-semiconductor (LDMOS) in this article. Radiation-induced dual-channel leakage current model is proposed to reveal the mechanism of leakage current generation at OFF-state. Radiation causes a mass of positive oxide trapped charges generated in field oxide (FOX) layer and buried oxide layer. Owing to the P-SOI layer with significantly low doping concentration, two inversion channels are formed at the surface and bottom in the edge termination region, which provides parallel conduction paths. Electrons from the source N+ are pulled down and flow along the bottom channel while punchthrough occurring. The radiation-induced leakage current could be suppressed by thinning FOX layer, increasing the doping concentration of the P-SOI layer, and thickening the SOI layer.

Evidence of Interface Trap Build-Up in Irradiated 14-nm Bulk FinFET Technologies

Total ionizing dose response of 14-nm bulk-Si FinFETs has been studied with a specially designed test chip. The radiation testing shows evidence of interface trap build-up on 14-nm Bulk FinFET technologies. These defects created in the isolation layer give rise to a new radiation-induced leakage path which might lead to a reliability issue in CMOS technologies at or below the 14-nm node. TCAD simulations are performed and an analytical model for TID-induced leakage current is presented to support analysis of the identified TID mechanism. TCAD simulation and analytical model results are consistent with the experimental data.

Processing and Interconnections of Finely Segmented Semiconductor Pixel Detectors for Applications in Particle Physics and Photon Detection

Radiation hardness is in the focus of the development of particle tracking and photon imaging detector installations. Semiconductor detectors, widely used in particle physics experiments, have turned into capacitive-coupled (AC-coupled) detectors from the originally developed conductively coupled (DC-coupled) detectors. This is due to the superior isolation of radiation-induced leakage current in AC-coupled detectors. However, some modern detector systems, such as the tracking detectors in the CERN LHC CMS or ATLAS experiments, are still DC-coupled. This originates from the difficulty of implementing AC coupling on very small pixel detector areas. In this report, we describe our advances in the detector processing technology. The first topic is the applications of the atomic layer deposition processing technology, which enables the very high densities of capacitance and resistance that are needed when the dimensions of the physical segmentation of pixel detectors need to be scaled down. The second topic is the flip-chip/bump-bonding interconnection technology, which is necessary in order to manufacture pixel detector modules on a large scale with a more than 99% yield of noise-free and faultless pixels and detector channels.

New Radiation-Hardened Design of a CMOS Instrumentation Amplifier and its Tolerant Characteristic Analysis

A radiation-hardened instrumentation amplifier (IA) that allows precise measurement in radiation environments, including nuclear power plants, space environments, and radiation therapy rooms, was designed and manufactured, and its characteristics were verified. Most electronic systems are currently designed using silicon-based complementary metal-oxide semiconductor (CMOS) integrated circuits (ICs) to achieve a highly integrated low-power design. However, fixed charges induced in silicon by ionization radiation cause various negative effects, resulting in, for example, the generation of leakage current in circuits, performance degradation, and malfunction. Given that such problems in radiation environments may directly lead to a loss of life or environmental contamination, it is critical to implement radiation-hardened CMOS IC technology. In this study, an IA used to amplify fine signals of the sensors was designed and fabricated in the 0.18 μm CMOS bulk process. The IA contained sub-circuits that ensured the stable voltage supply needed to implement system-on-chip (SoC) solutions. It was also equipped with special radiation-hardening technology by applying an I-gate n-MOSFET that blocks the radiation-induced leakage currents. Its ICs were verified to provide the intended performance following a total cumulative dose of up to 25 kGy(Si), ensuring its safety in radiation environments.

Observation of Radiation-Induced Leakage Current Defects in MOS Oxides With Multifrequency Electrically Detected Magnetic Resonance and Near-Zero-Field Magnetoresistance

We report high and low-frequency electrically detected magnetic resonance measurements and near-zero-field magnetoresistance measurements on radiation-induced leakage currents in irradiated Si/SiO2 metal-oxide-silicon (MOS) structures. This study identifies the chemical and physical nature of atomic-scale defects involved in radiation-induced leakage currents in SiO2 using an analytical technique. Our results suggest that trap-assisted tunneling through these Si/SiO2 structures involves Pb centers (silicon dangling bonds at the Si/SiO2 interface), rather than only ${E}$ ’ centers (oxygen vacancies in the SiO2 film). We utilize simulations of the defects’ resonance spectra to provide further evidence for the involvement of interface Pb centers in the radiation-induced leakage currents. These simulations also explore the possibility of additional ${E}$ ’ center involvement in the radiation-induced leakage currents.

Ionization Damage Effects of Pulse Discharge Circuit Switched by Anode-Short MOS-Controlled Thyristor

The MOS-controlled Thyristor (MCT) has been characterized by MOS-gating, high current rise rate, and high blocking capabilities. The anode short MCT (AS-MCT) is distinguished from the conventional MCT by an anode-short structure, which forms an extracting path for the leakage current at the gate-ground and develops a normally-off characteristic. The AS-MCTs are ideal switches for pulse discharge application. As a composite structure made of metal-oxide-silicon and bipolar junction transistors, AS-MCT is susceptible to ionization damage. This work reports the experimental results for the degradation of zero-load (or short) pulse discharge circuit characteristics induced by the ionization damage of its AS-MCT switch following cobalt-60 γ-ray dose up to 9160 Gy(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). The radiation-induced leakage current in AS-MCT accounts for the degradations of charging time and peak surging current of the pulse discharge circuit. These degradations show a “tick”-like dependence on the γ-ray dose which are recoverable after high dose exposures, thousands of Gy(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). From device and circuit physics perspectives, the damages on pulse discharge circuit are modelled, and then, this article proposes, the mechanism behind the characteristics degradation of pulse discharge circuit from the total ionization dose damage of AS-MCT switch.

Total-Ionizing-Dose Effects and Low-Frequency Noise in 30-nm Gate-Length Bulk and SOI FinFETs With SiO2/HfO2Gate Dielectrics

Total-ionizing-dose (TID) effects and low-frequency noise are evaluated in 30-nm gate-length bulk and silicon-on-insulator (SOI) FinFETs for devices with fin widths of 10–40 nm. Minimal threshold voltage shifts are observed at 2 Mrad(SiO2), but large increases in low-frequency noise are found, and significant changes in defect-energy distributions are inferred. Radiation-induced leakage current is enhanced for narrow- and short-channel bulk FinFETs. Short-channel SOI FinFETs show enhanced degradation compared with longer-channel devices. Narrow- and short-channel SOI devices exhibit high radiation tolerance. Significant random telegraph noise (RTN) is observed in smaller devices due to prominent individual defects.

Investigating the latent reliability degradation of partially depleted SOI devices induced by high-energy heavy ions irradiation

Through electrical stress and annealing experiments performed on irradiated partially depleted SOI MOS devices, high-energy heavy ions induced defects in the gate oxide are shown to affect insulation character and the long time reliability of the devices. A decrease of the time-dependent dielectric breakdown (TDDB) lifetime and an increase of the radiation-induced leakage current (RILC) were observed after irradiation at the nominal operating irradiation bias. But then, the RILC was completely removable using isochronal annealing experiment, while the TDDB lifetime did not increase back to its initial value. We interpreted these results and degeneration mechanisms in terms of the neutral electrons traps and morphological oxide defects induced by high-energy heavy ions, which may be meaningful to evaluate the reliability of the devices used in the radiation environment.