Total Ionizing Dose Radiation Effects on MOS Transistors with Different Layouts

Both nMOS and pMOS transistors with two-edged and multi-finger layouts are fabricated in a standard commercial 0.6μm CMOS/bulk process to study their total ionizing dose （TID） radiation effects. The leakage current, threshold voltage shift, and transconductance of the devices are monitored before and after T-ray irradiation. Different device bias conditions are used during irradiation. The experiment results show that TID radiation effects on nMOS devices are very sensitive to their layout structures. The impact of the layout on TID effects on pMOS devices is slight and can be neglected.

AGGLOMERATION AND RADIATION EFFECT OF THE PULL OF URBANIZATION

In order to explore the train of thought for China’s urbanizing development and coordinated rural economic development, and to find good ways of solving rural problems through urbanization, this paper absorbs the push-and-pull forces theory and the systematic dynamic theory in the traditional population migration theories, views urbanization as a dynamic system, makes research on the push-and-pull mechanism of urbanization. The pulling power of urbanization is analyzed according to two aspects, the agglomeration effect and the radiation effect of cities. The agglomeration effect provides continuous propelling force for urbanization, and the radiation effect further accelerates the urbanization process by pushing forward the development of rural economy. Of course, the slow development of urbanization can result in the hindrance to rural economic development.

Study of total ionizing dose radiation effects on enclosed gate transistors in a commercial CMOS technology

This paper studies the total ionizing dose radiation effects on MOS （metal-oxide-semiconductor） transistors with normal and enclosed gate layout in a standard commercial CMOS （compensate MOS） bulk process. The leakage current, threshold voltage shift, and transconductance of the devices were monitored before and after γ-ray irradiation. The parameters of the devices with different layout under different bias condition during irradiation at different total dose are investigated. The results show that the enclosed layout not only effectively eliminates the leakage but also improves the performance of threshold voltage and transconductance for NMOS （n-type channel MOS） transistors. The experimental results also indicate that analogue bias during irradiation is the worst case for enclosed gate NMOS. There is no evident different behaviour observed between normal PMOS （p-type channel MOS） transistors and enclosed gate PMOS transistors.

Proton radiation effect on GaAs/AlGaAs core–shell ensemble nanowires photo-detector

We demonstrate that the GaAs/AlGaAs nanowires（NWs） ensemble is fabricated into photo-detectors. Current–voltage（I–V） characteristics are measured on Ga As/Al Ga As core–shell ensemble NW photo-detectors at room-temperature before and after 1-MeV proton irradiation with fluences from 1.0 × 10^（13） cm^（-2） to 5.0 × 10^（14） cm^（-2）. The degradation of photocurrent suggests that the point defects induced by proton radiation could cause both carrier lifetime and carrier mobility to decrease synchronously. Comparing with a GaAs quantum well, the degradations of light and dark current for the irradiated NWs photo-detector indicate that NWs material is a preferable potential candidate for space applications.

Radiation effects on MOS and bipolar devices by 8 MeV protons,60 MeV Br ions and 1 MeV electrons

The radiation effects of the metal-oxide-semiconductor （MOS） and the bipolar devices are characterised using 8 MeV protons, 60 MeV Br ions and 1 MeV electrons. Key parameters are measured in-situ and compared for the devices. The ionising and nonionising energy losses of incident particles are calculated using the Geant4 and the stopping and range of ions in matter code. The results of the experiment and energy loss calculation for different particles show that different incident particles may give different contributions to MOS and bipolar devices. The irradiation particles, which cause a larger displacement dose within the same chip depth of bipolar devices at a given total dose, would generate more severe damage to the voltage parameters of the bipolar devices. On the contrary, the irradiation particles, which cause larger ionising damage in the gate oxide, would generate more severe damage to MOS devices. In this investigation, we attempt to analyse the sensitivity to radiation damage of the different parameter of the MOS and bipolar devices by comparing the irradiation experimental data and the calculated results using Geant4 and SRIM code.

Radiation Effect of Neutrons in a Reactor on Polyurethane

The radiation effect of neutrons in a reactor on polyurethane was studied.The gases produced by irradiated samples were analyzed by gas chromatography,and the dynamic mechanical and compression properties of the samples were also studied.The positron annihilation lifetime of irradiated samples was measured at room temperature in vacuum.The experimental results indicate that gas chromatography is a powerful tool to quantitatively analyze the gas products from neutron-irradiated polyurethane and characterizes the chemical changes in the sample.And the changes in microstructure determined from the PAL correlate well with the measurements of the mechanical properties by dynamic mechanical analysis（DMA）.

Total Ionizing Dose Radiation Effects in the P-Type Polycrystalline Silicon Thin Film Transistors

The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measured before and after radiation. The experimental results show that threshold voltage and hole-field-effect mobility decrease, while sub-threshold swing and low-frequency noise increase with the increase of the total dose. The contributions of radiation induced interface states and oxide trapped charges to the shift of threshold voltage are also estimated. Furthermore, spatial distributions of oxide trapped charges before and after radiation are extracted based on the LFN measurements.

Ionizing radiation effect on single event upset sensitivity of ferroelectric random access memory

The impact of ionizing radiation effect on single event upset（SEU） sensitivity of ferroelectric random access memory（FRAM） is studied in this work. The test specimens were firstly subjected to ^60Co γ-ray and then the SEU evaluation was conducted using ^209Bi ions. As a result of TID-induced fatigue-like and imprint-like phenomena of the ferroelectric material, the SEU cross sections of the post-irradiated devices shift substantially. Different trends of SEU cross section with elevated dose were also found, depending on whether the same or complementary test pattern was employed during the TID exposure and the SEU measurement.

Radiation Effects on the Immunological Functions and Membranes of Alveolar Macrophages of Rats

Alveolar macrophages (AM) from BCG activated Wistar rat were irradiated with different doses of Gamma rays in vitro. The effects of radiation on their immunological functions and membrane damage were studied. The non-specific cytotoxicity and specific phagocytosis of AM irradiated with dose of 0, 100, 300 and 500 Gy decreased with the increase in dose. The relative fractions of Lactate Dehydrogenase and Beta-glucuronidase (β-glu) activity in supernatant increased with the increase in dose. There was a correlation between the suppression of immunological functions and the degree of damage of cytoplasmic and lysosomal membranes of AM after irradiation. Na2SeO3, a protective agent of cell membranes, alleviated this effect on the suppressive cytotoxicity indices of irradiated AM.

2 GeV Electron Beam Irradiation Effects in Advanced Metallic Glasses

Six amorphous alloys (Alloy 1: Fe56Co24Nb4B13Si2Cu1, Alloy 2: Fe68.5Co5Nb3Cu1Si15.5B7, Alloy 3: Fe75.3Ni0.8Cr0.9Si8.7B14.3, Alloy 4: Fe56Co24Cr10Nb4B3Si1Cu2, Alloy 5: Fe72.9Nb3Cu1Si16.2B6.9, Alloy 6: Fe83.3Si8.6Nb5.5B1.4Cu1.2) were selected in terms of their composition and magnetostriction constants and uniformly irradiated in a high radiation environment in Hall A of the Thomas Jefferson National Accelerator Facility. The 2 GeV electron beam irradiation-induced effects were characterized by Mӧssbauer spectroscopy. The microstructural changes were related to the evolution of the hyperfine magnetic field distributions and isomer shifts. In particular, the occurrence of stress centers in the amorphous materials was evidenced.

Simulation of the Ecosystem Productivity Responses to Aerosol Diffuse Radiation Fertilization Effects over the Pan-Arctic during 2001–19

The pan-Arctic is confronted with air pollution transported from lower latitudes.Observations have shown that aerosols help increase plant photosynthesis through the diffuse radiation fertilization effects(DRFEs).While such DRFEs have been explored at low to middle latitudes,the aerosol impacts on pan-Arctic ecosystems and the contributions by anthropogenic and natural emission sources remain less quantified.Here,we perform regional simulations at 0.2o×0.2ousing a well-validated vegetation model(Yale Interactive terrestrial Biosphere,YIBs)in combination with multi-source of observations to quantify the impacts of aerosol DRFEs on the net primary productivity(NPP)in the pan-Arctic during 2001-19.Results show that aerosol DRFEs increase pan-Arctic NPP by 2.19 Pg C(12.8%)yr^(-1)under clear-sky conditions,in which natural and anthropogenic sources contribute to 8.9% and 3.9%,respectively.Under all-sky conditions,such DRFEs are largely dampened by cloud to only 0.26 Pg C(1.24%)yr^(-1),with contributions of 0.65% by natural and 0.59% by anthropogenic species.Natural aerosols cause a positive NPP trend of 0.022% yr^(-1)following the increased fire activities in the pan-Arctic.In contrast,anthropogenic aerosols induce a negative trend of-0.01% yr^(-1)due to reduced emissions from the middle latitudes.Such trends in aerosol DRFEs show a turning point in the year of 2007 with more positive NPP trends by natural aerosols but negative NPP trends by anthropogenic aerosols thereafter.Though affected by modeling uncertainties,this study suggests a likely increasing impact of aerosols on terrestrial ecosystems in the pan-Arctic under global warming.

Analysis of Heat Transport in a Powell-Eyring Fluid with Radiation and Joule Heating Effects via a Similarity Transformation

Heat transfer in an Eyring-Powell fluid that conducts electricity and flows past an exponentially growing sheet is considered.As the sheet is stretched in the x direction,the flow develops in the region with y>0.The problem is tackled through a set of partial differential equations accounting for Magnetohydrodynamics(MHD),radiation and Joule heating effects,which are converted into a set of equivalent ordinary differential equations through a similarity transformation.The converted problem is solved in MATLAB in the framework a fourth order accurate integration scheme.It is found that the thermal relaxation period is inversely proportional to the thickness of the thermal boundary layer,whereas the Eckert-number displays the opposite trend.As this characteristic number grows,the temperature within the channel increases.

Effects of Si Ion Implantation on the Total-Dose Radiation Properties of SIMOX SOI Materials

To improve the total-dose radiation hardness,silicon-on-insulator （SOI） wafers fabricated by the separation-by-implanted-oxygen （SIMOX） method are modified by Si ion implantation into the buried oxide with a post anneal. The ID- VG characteristics can be tested with the pseudo-MOSFET method before and after radiation. The results show that a proper Si-ion-implantation method can enhance the total-dose radiation tolerance of the materials.

Radiation-hardened property of single-walled carbon nanotube film-based field-effect transistors under low-energy proton irradiation

Strong C-C bonds,nanoscale cross-section and low atomic number make single-walled carbon nanotubes(SWCNTs)a potential candidate material for integrated circuits(ICs)applied in outer space.However,very little work combines the simulation calculations with the electrical measurements of SWCNT field-effect transistors(FETs),which limits further understanding on the mechanisms of radiation effects.Here,SWCNT film-based FETs were fabricated to explore the total ionizing dose(TID)and displacement damage effect on the electrical performance under low-energy proton irradiation with different fluences up to 1×1015 p/cm2.Large negative shift of the threshold voltage and obvious decrease of the on-state current verified the TID effect caused in the oxide layer.The stability of the subthreshold swing and the off-state current reveals that the displacement damage caused in the CNT layer is not serious,which proves that the CNT film is radiation-hardened.Specially,according to the simulation,we found the displacement damage caused by protons is different in the source/drain contact area and channel area,leading to varying degrees of change for the contact resistance and sheet resistance.Having analyzed the simulation results and electrical measurements,we explained the low-energy proton irradiation mechanism of the CNT FETs,which is essential for the construction of radiation-hardened CNT film-based ICs for aircrafts.

Experimental research on transient radiation effects in microprocessors based on SPARC-V8 architecture

An experimental system is developed for the transient radiation effects testing of an anti-radiation hardened processor. Based on this system, the transient radiation effects in a microprocessor based on SPARC-V8 architecture was investigated. The dose-rate-soft-error index parameters of the processor were determined according to the test results, as were the influences on the function and timing parameters of the processor. The power supply balance is affected, which caused the system to reset and be the main source of soft errors. The results showed the circuit recovery time is primarily determined by the internal PLL, while the core power and the output-low-IO ports are more sensitive to the transient dose rate effect. The power-integrity-hardened design is proposed to mitigate the transient radiation effect.

Investigation of thermal radiation effect on optical dome of sapphire coated yttrium oxide

Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapphire optical dome coated with yttrium oxide by a radio frequency mag- netron sputtering method. The emissivity of sapphire coated with Y203 films is studied by both numerical and experi- mental methods. The results indicate that the emissivity of sapphire substrate is reduced effectively with increasing the thickness of the Y203 film. In addition, a finite element model is developed to simulate the radiation intensity of the optical dome. The thermal responses indicate that the max- imum temperature is reduced apparently compared with the uncoated sapphire as Y203 film thicknesses increase. The average irradiance distribution at different film thicknesses with time shows that the self-thermal radiation disturbance of sapphire optical dome delays 0.93 s when the thickness of Y203 film is 200μm, which can guarantee the dome works properly and effectively even in a harsh environment.

Total dose radiation effects on SOI NMOS transistors with different layouts

Partially-depleted Silicon-On-Insulator Negative Channel Metal Oxide Semiconductor （SOI NMOS） transistors with different layouts are fabricated on radiation hard Separation by IMplanted OXygen （SIMOX） substrate and tested using 10 keV X-ray radiation sources. The radiation performance is characterized by transistor threshold voltage shift and transistor leakage currents as a function of the total dose up to 2.0×10^6 rad（Si）. The results show that the total dose radiation effects on NMOS devices are very sensitive to their layout structures.

Effect of bias condition on heavy ion radiation in bipolar junction transistors

The characteristic degradations in a silicon NPN bipolar junction transistor （BJT） of 3DG142 type are examined under irradiation with 40-MeV chlorine （C1） ions under forward, grounded, and reverse bias conditions, respectively. Different electrical parameters are in-situ measured during the exposure under each bias condition. From the experimental data, a larger variation of base current （IB） is observed after irradiation at a given value of base-emitter voJtage （VBE）, while the collector current is slightly affected by irradiation at a given VBE. The gain degradation is affected mostly by the behaviour of the base current. From the experimental data, the variation of current gain in the case of forward bias is much smaller than that in the other conditions. Moreover, for 3DG142 BJT, the current gain degradation in the case of reverse bias is more severe than that in the grounded case at low fluence, while at high fluence, the gain degradation in the reverse bias case becomes smaller than that in the grounded case.

Effect of heavy ion irradiation on the interface traps of AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors(HEMTs)were irradiated with heavy ions at various fluences.After irradiation by 2.1 GeV^(181) Ta^(32+) ions,the electrical characteristics of the devices significantly decreased.The threshold voltage shifted positively by approximately 25%and the saturation currents decreased by approximately 14%.Defects were induced in the band gap and the interface between the gate and barrier acted as tunneling sites,which increased the gate current tunneling probability.According to the pulsed output characteristics,the amount of current collapse significantly increased and more surface state traps were introduced after heavy ion irradiation.The time constants of the induced surface traps were mainly less than 10μs.

Proton radiation effect of NPN-input operational amplifier under different bias conditions

NPN-input bipolar operational amplifiers LM741 were irradiated with ^60Coγ-ray, 3 MeV protons and10 MeV protons respectively at different biases to investigating the proton radiation response of the NPN-input operational amplifier. The comparison of protons with^60Coγ-rays showed that the proton radiation mainly induced ionization damage in LM741. Under different bias conditions, the radiation sensitivity is different; zero biased devices show more radiation sensitivity in the input biased current than forward biased devices. Supply current（±Icc）is another parameter that is sensitive to proton radiation,^60Coγ-ray, 3 MeV and 10 MeV proton irradiation would induce a different irradiation response in ±Icc, which is caused by different ionization energy deposition and displacement energy deposition of^60Coγ-ray, 3 MeV and 10 MeV proton irradiation.