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1.
本文研究了电子、γ射线辐照MOS器件、电容引起的平带电压漂移ΔV_(FB)和阈电压漂移ΔV_(TP)与氧化层厚度T_(OX)和总剂量D的关系。实验得到:在+10V偏置辐照下,Δ_V(FB)∝T_(OX)~3;在导通偏置辐照下,ΔV_(TH)∝T_(OX)~3D~(2/3);在零偏置辐照下,ΔV_(TP)∝T_(OX)~2D~(2/3)。运用Viswanathan模型解释了实验结果。并根据~T_(OX)~3关系简单讨论了MOS器件抗辐射加固工艺的优化问题。  相似文献   

2.
半导体器件与电路辐照响应测试系统   总被引:3,自引:3,他引:0  
任迪远  高文钰 《核技术》1994,17(9):542-547
介绍用于测量MOS电容、MOSFET、半导体元器件和集成电路辐照效应的微机测试系统及其功能,并给出该系统在半导体辐射损伤研究甲的应用实例.  相似文献   

3.
The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line Prompt Gamma Neutron Activation Analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a general method applicable to Gamma spectra processing is presented and applied to PGNAA in mineral industry. Based on the Fourier transform of spectra and their de-correlation in the Fourier space (the improvement of the conditioning of the correlation matrix), processing of overlapping of characteristic peaks minimizes the propagation of random errors, which optimizes the accuracy and decreases the detection limits of elemental analyses. In comparison with classical methods based on the linear combinations of relevant regions of spectra the improvement may be considerable, especially when several elements are interfering. The method is applied to four case stories covering both borehole logging and on-line analysis on conveyor belt of raw materials.  相似文献   

4.
Radiation sensors based on metal oxide semiconductor (MOS) structure are useful because of their superior sensitivity as well as excellent compatibility with the existing microelectronic technology. In this paper, a systematic study of MOS capacitors built on p- and n-type Si substrates with different SiO2 thicknesses (10 nm, 50 nm, 100 nm and 240 nm) is presented. MOS device response to gamma radiation up to 256 Gray have been studied from the sensor application point of view. Variation of the radiation induced device response with oxide thickness, substrate type, applied bias and post annealing have been measured and discussed. Radiation induced charge in MOS devices is shown to be a strong function of the oxide thickness as expected. Application of a positive bias to the gate is found to enhance the device sensitivity for both n- and p-type devices. This is explained in terms of the involvement of the interface states in the sensing process. Devices have also been studied after repeated cycles of irradiation and annealing treatment under hydrogen atmosphere. Each cycle consists of gamma irradiation with 60 Gray dose and an anneal at 200 °C for 30 min. The charging-discharging mechanism during these cycles is discussed.  相似文献   

5.
Variation of the ion beam induced charge (IBIC) pulse heights due to ion irradiation was investigated on a Si pn diode and a 6H-SiC Schottky diode using a 2 Mev He+ micro-beam. Each diode was irradiated with a focused 2 MeV He+ micro-beam to a fluence in the range of 1×109–1×1013 ions/cm2. Charge pulse heights were analyzed as a function of the irradiation fluence. After a 2 MeV ion irradiation to the Si pn junction diode, the IBIC pulse height decreased by 15% at 9.2×1012 ions/cm2. For the SiC Schottky diode, with a fluence of 6.5×1012 ions/cm2, the IBIC pulse height decreased by 49%. Our results show that the IBIC method is applicable to evaluate irradiation damage of Si and SiC devices and has revealed differences in the radiation hardness of devices dependent on both structural and material.  相似文献   

6.
7.
The effects of short duration irradiation with low dose rate gamma and beta rays on the input resistance and the output Hall voltage of InSb, GaAs, Si, and Ge semiconductor Hall effect devices were systemically studied. Both gamma and beta irradiation can cause the input resistance of Hall effect devices to increase linearly with increasing irradiation time, in the absence of a magnetic field. When the devices were placed in a magnetic field, the output Hall voltage and input resistance increased nonlinearly with increasing gamma irradiation time. The effects of both gamma and beta irradiation persisted long after the irradiation itself, and without annealing. The effects from irradiation in Hall effect devices can be mainly ascribed to the degradation of the charge carriers’ transport properties caused by radiation-induced defects. The radiation resistance of the Hall effect devices was estimated by considering changes of the input resistance under the same irradiation conditions. The Ge and Si Hall effect devices demonstrated a better radiation resistance than the InSb and GaAs Hall effect devices due to their large displacement threshold energy.  相似文献   

8.
The influence of the oxide layer morphology on the hydrogen uptake during steam oxidation of (Zr,Sn) and Zr-Nb nuclear fuel rod cladding alloys was investigated in isothermal separate-effect tests and large-scale fuel rod bundle simulation experiments. From both it can be concluded that the concentration of hydrogen in the remaining metal strongly depends on the existence of tangential cracks in the oxide layers formed by the tetragonal - monoclinic phase transition in the oxide, known as breakaway effect. In these cracks hydrogen is strongly enriched. It results in very local high hydrogen partial pressure at the oxide/metal interface and in an increase of the hydrogen concentration in the metal at local regions where such cracks in the oxide layer exist. Due to this effect the hydrogen uptake of the remaining zirconium alloy does not depend monotonically on temperature. Differences between (Zr,Sn) and Zr-Nb alloys are caused by differences in the hydrogen production due to different oxidation kinetics and in the crack forming phase transformation in the oxides as well as in the mechanical stability of the oxides.  相似文献   

9.
The CINS (Combined Ion and Neutron Spectrometer) consists of three detector systems: a boron-loaded plastic scintillator for medium energy neutrons, a silicon detector system for high-energy neutrons, and a charged particle stack containing both silicon detectors and scintillators. A readout system built for the charged particle stack is described here. The stack must be able to detect particles over a wide range of charge and energy. It contains 7 detectors, including 4 silicon detectors that each have two output paths. The readout must have a large usable dynamic range and must be able to handle the relatively high event rates that occur when the stack is placed in an accelerator beam. The data acquisition system detects events (that is, compares incoming signals to user-supplied trigger definitions), proceeds to capture waveform data from the preamplifiers, and saves the data to a hard drive. Although only used with the charged particle stack to date, the system can also be used with the other elements of CINS.  相似文献   

10.
ABSTRACT

Typical metal oxide corrosion products of structural materials have been irradiated with γ-rays in ultra-pure water to investigate the effect of radiation on the surface oxide and the nature of adsorbed water. Analysis techniques including thermal gravimetric analysis, differential thermal analysis, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy before and after γ-irradiation were employed to investigate surface structural effects and adsorbed water behaviour. The production of H2 in the oxide nanoparticle mixtures was investigated by gas chromatography to probe the mechanism of radiolysis in the water/oxide mixtures and the relationship with surface water. The nature of water at the surface of the oxides was affected by γ-radiation and the relationship was dependent on the particle composition. The rate of H2 production was shown to be oxide dependent, and higher rates of H2 formation were attributed to the decomposition of surface adsorbed water. Changes to the surface chemistry and H2 production rates were found to be highly dependent on the surface chemistry of the metal oxide nanoparticle and no bulk structural changes were observed.  相似文献   

11.
医疗器械辐射灭菌的现状及进展   总被引:8,自引:0,他引:8  
朱南康  王春雷  滕维芳 《核技术》2003,26(3):189-196
本文叙述了医疗器械辐射灭菌的特点和在国内外的发展概况。论述了医疗器械辐射灭菌的几个关键问题:建立现代化的工业辐射灭菌工厂;建立完善的剂量监测系统;灭菌剂量的设定与验证;灭菌工艺的确认;日常加工的过程控制;网络管理和防伪标识;质量体系的认证和建设;辐射防护和安全等。同时提出了我国的医疗器械辐射灭菌事业在当前和今后一个时期内应关注的几个关键问题:机遇与发展;质量体系建设与国际水平接轨;现代企业制度的建设等。  相似文献   

12.
The Combined Ion and Neutron Spectrometer, CINS, is designed to measure the charged and neutral particles that contribute to the radiation dose and dose equivalent received by humans in spaceflight. As the depth of shielding increases, either onboard a spacecraft or in a surface habitat, the relative contribution of neutrons increases significantly, so that obtaining accurate neutron spectra becomes a critical part of any dosimetric measurements. The spectrometer system consists of high- and medium-energy neutron detectors along with a charged-particle detector telescope based on a standard silicon stack concept. The present version of the design is intended for ground-based use at particle accelerators; future iterations of the design can easily be streamlined to reduce volume, mass, and power consumption to create an instrument package suitable for spaceflight. The detector components have been tested separately using high-energy heavy ion beams at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory and neutron beams at the Radiological Research Accelerator Facility operated by Columbia University. Here, we review the progress made in fabricating the hardware, report the results of several test runs, and discuss the remaining steps necessary to combine the separate components into an integrated system. A custom data acquisition system built for CINS is described in an accompanying article.  相似文献   

13.
Cooling and solidification of metal oxide droplets in water are considered, using a single-particle model which takes into account heat conduction and thermal radiation transfer within the particle. It is shown that, for millimeter-size particles, near-infrared absorption of the particle's substance determines the solidification pattern and dynamics. For semi-transparent aluminum oxide particles, the rate of surface solidification is controlled by convective heat transfer. For opaque corium particles, thermal radiation from the particle surface leads to fast surface solidification. The impact of so-formed crust layer on subsequent particle fragmentation is discussed with respect to its influence on steam explosion.  相似文献   

14.
A change of wave form of current transients induced by a single heavy ion was investigated around a pn junction with 8 μm width and 10 μm length as a function of the ion incident position. Three pn junctions were made on a 3 μm thick Si epilayer (1 × 1016/cm3) grown on Si substrate and were in a line along an aluminum electrode with 10 μm spacing between the adjacent junctions. The elements of a pn junction array were irradiated with a 1 μm diameter 15 MeV C+ heavy ion microbeam spacing steps by 3 μm. At a bias voltage of − 10 V, 148, 91, and 54 fC were collected at the pn junction center, and at 3 μm and 4 μm from the edge of the electrode, respectively. Internal device structure was examined by IBIC (ion beam induced current) method by using a 2 MeV He+ ion microbeam. From the IBIC spectrum and the IBIC image, the charge collected from the open space by the diffusion process was observed in addition to the charge collected from the depletion layer of the pn junction.  相似文献   

15.
Silicon Carbide (SiC) semiconductor radiation detectors are being developed for alpha-particle, X-ray and Gamma-ray, and fast-neutron energy spectrometry. SiC detectors have been operated at temperatures up to 306 °C and have also been found to be highly resistant to the radiation effects of fast-neutron and charged-particle bombardments. In the present work, the alpha-particle response of a SiC detector based on a Schottky diode design has been carefully monitored as a function of 137Cs gamma-ray exposure. The changes in response have been found to be negligible for gamma exposures up to and including 5.4 MGy, and irradiations to higher doses are in progress.  相似文献   

16.
MeV ion beam lithography is a direct writing technique capable of producing microfluidic patterns and lab-on-chip devices with straight walls in thick resist films. In this technique a small beam spot of MeV ions is scanned over the resist surface to generate a latent image of the pattern. The microstructures in resist polymer can be then revealed using a chemical developer that removes exposed resist, while leaving unexposed resist unaffected. In our system the size of the rectangular beam spot is programmably defined by two L-shaped tantalum blades with well-polished edges. This allows rapid exposure of entire rectangular pattern elements up to 500 × 500 μm in one step. By combining different dimensions of the defining aperture with the sample movements relative to the beam spot, entire fluidic patterns with large reservoirs and narrow flow channels can be written over large areas in short time. Fluidic patterns were written in PMMA using 56 MeV 14N3+ and a 3 MeV 4He2+ beams from K130 cyclotron and a 1.7 MV Pelletron accelerators, respectively, at the University of Jyväskylä Accelerator Laboratory. The patterns were characterized using SEM, and the factors affecting patterns quality are discussed.  相似文献   

17.
The yields and spatial distribution of the products arising from the in source oxidation of 50 μm LDPE films induced by 60-Co gamma radiations and by 300 kev electrons have been investigated as a function of the dose rate. The dose rate was found to have a strong influence on the reaction, the hydroperoxides and carbonyls yields at the lowest gamma dose rate of 0.04 kGy/h being decreased by a factor of about three with increasing the gamma dose rate up to 0.69 kGy/h and by a factor of about 30 when operating at the e-beam dose rate of 1.5 kGy/s. The carbonyls depth concentration profiles, the EPR measurements on radicals intermediates and the experiments of post-irradiation oxidation are consistent with the conclusion that, as far as the gamma irradiation is concerned, the observed dose rate effects cannot be imputed to oxygen diffusion control and/or to the chain branching via hydroperoxides decomposition coupled to the longer times between the initiation events. The hypothesis of the dose rate acting on the kinetic chain length of the radioxidation which in turn implies a substantially uniform distribution of radicals in the amorphous phase attained through spur expansion is proposed.  相似文献   

18.
The use of Al2O3 dielectric in MOS based radiation sensors has been investigated. Their response has been compared with conventional MOS capacitors with a SiO2 dielectric. The study includes gamma radiation effects with dose up to 4 Gy. The effect of radiation has been determined from the valance band shift in C-V curves. The amount of charge induced by the radiation has been calculated and compared with the response of MOS capacitors with SiO2 with the same and different thicknesses. Fading properties have been studied and compared. Results show that MOS capacitors with Al2O3 dielectric exhibit sensitivity greater than that obtained from MOS capacitors with SiO2. This higher sensitivity is attributed to higher trapping efficiency in the Al2O3 layer.  相似文献   

19.
本文介绍10—12MeV高能电子对MOS样品及已封装硅二、三极管辐射效应的实验研究结果。分析了高能电子辐射效应的特点及其实用意义。  相似文献   

20.
The Au/SiO2/n-Si (MOS) structures were exposed to beta-ray irradiation to a total dose of 30 kGy at room temperature. Irradiation effect on dielectric properties of MOS structures were investigated using capacitance−voltage (CV) and conductance−voltage (G/ω−V) characteristics. The CV and G/ω−V measurements carried out in the frequency range from 1 kHz to 10 MHz and at various radiation doses, while the dc voltage was swept from positive bias to negative bias for MOS structures. The dielectric constant (ε′), dielectric loss (ε″), loss factor (tan δ) and ac electrical conductivity (σac) were calculated from the CV and G/ωV measurements and plotted as a function of frequency at various radiation doses. A decrease in the ε′ and ε″ were observed when the irradiation dose increased. The decrease in the ε′ and ε″ of irradiated MOS structures in magnitude is explained on the basis of Maxwell−Wagner interfacial polarization. Also, the σac is found to decrease with increasing radiation dose. In addition, the values of the tan δ decrease with increasing radiation dose and give a peak. From the experimental results, it is confirmed that the peak of loss tangent is due to the interaction between majority carriers and interface states which induced by radiation.  相似文献   

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