Neutron irradiation effects on AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors (HEMTs) were exposed to 1 MeV neutron irradiation at a neutron fluence of 1 × 10¹⁵ cm^-2. The dc characteristics of the devices, such as the drain saturation current and the maximum transconductance, decreased after neutron irradiation. The gate leakage currents increased obviously after neutron irradiation. However, the rf characteristics, such as the cut-off frequency and the maximum frequency, were hardly affected by neutron irradiation. The AlGaN/GaN heterojunctions have been employed for the better understanding of the degradation mechanism. It is shown in the Hall measurements and capacitance-voltage tests that the mobility and concentration of two-dimensional electron gas (2DEG) decreased after neutron irradiation. There was no evidence of the full-width at half-maximum of X-ray diffraction (XRD) rocking curve changing after irradiation, so the dislocation was not influenced by neutron irradiation. It is concluded that the point defects induced in AlGaN and GaN by neutron irradiation are the dominant mechanisms responsible for performance degradations of AlGaN/GaN HEMT devices.     

Neutron irradiation effects on A1GaN//GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors(HEMTs) were exposed to 1 MeV neutron irradiation at a neutron fluence of 1 × 10 15 cm 2.The dc characteristics of the devices,such as the drain saturation current and the maximum transconductance,decreased after neutron irradiation.The gate leakage currents increased obviously after neutron irradiation.However,the rf characteristics,such as the cut-off frequency and the maximum frequency,were hardly affected by neutron irradiation.The AlGaN/GaN heterojunctions have been employed for the better understanding of the degradation mechanism.It is shown in the Hall measurements and capacitance-voltage tests that the mobility and concentration of two-dimensional electron gas(2DEG) decreased after neutron irradiation.There was no evidence of the full-width at half-maximum of X-ray diffraction(XRD) rocking curve changing after irradiation,so the dislocation was not influenced by neutron irradiation.It is concluded that the point defects induced in AlGaN and GaN by neutron irradiation are the dominant mechanisms responsible for performance degradations of AlGaN/GaN HEMT devices.     

10位CMOS数模转换器在中子和γ混合环境下的综合辐射效应

研究了在反应堆中子和γ射线综合辐照环境下CMOS工艺10位数模转换器(DAC)的辐射效应。通过对DAC在γ辐射环境、中子辐射环境、中子和γ混合辐射环境以及中子预辐照后进行γ射线辐照下的效应对比发现,在中子和γ混合辐射环境下会产生电离总剂量效应加剧现象,即一定混合程度的中子和γ同时辐照会增强CMOS器件的辐射效应。     

Influence of radiational damage on the background of internal friction

It is experimentally established that, with the accumulation of radiational defects arising in neutron irradiation, the high-temperature background of internal friction of iron and nickel samples decreases. A hypothesis regarding the possible mechanism of this effect is proposed. A simple expression is given for estimating the magnitude of the background.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 32–36, June, 1984.     

Study of neutron irradiation effect on Morin transition in hematite

It is established by Mössbauer spectroscopy and slow neutron diffraction that temperature range of Morin transition in hematite changes depending on neutron irradiation dose, and above some critical values the transition is not observed at all. A fraction of iron ions with high-temperature orientation of moments which cause the sample weak-ferromagnetic characteristics decreases with temperature fall but does not disappear completely, and near 4 K it even rises. It is established that radiation defects causing the changes in Morin transition disappear at annealing of hematite on air at temperatures of 400–500 K.     

中子辐照对AlGaN/GaN高电子迁移率晶体管器件电特性的影响

本文采用能量为1 MeV的中子对SiN钝化的AlGaN/GaN HEMT(高电子迁移率晶体管)器件进行了最高注量为1015cm-2的辐照.实验发现:当注量小于1014cm-2时,器件特性退化很小,其中栅电流有轻微变化(正向栅电流IF增加,反向栅电流IR减小),随着中子注量上升,IR迅速降低.而当注量达到1015cm-2时,在膝点电压附近,器件跨导有所下降.此外,中子辐照后,器件欧姆接触的方块电阻退化很小,而肖特基特性退化却相对明显.通过分析发现辐照在SiN钝化层中引入的感生缺陷引起了膝点电压附近漏电流和反向栅泄漏电流的减小.以上结果也表明,SiN钝化可以有效地抑制中子辐照感生表面态电荷,从而屏蔽了绝大部分的中子辐照影响.这也证明SiN钝化的AlGaN/GaN HEMT器件很适合在太空等需要抗位移损伤的环境中应用.     

Modeling the Behavior of a MOS Transistor under Fast Neutron and Gamma Irradiation

A numerical model of trapping of the radiation-induced charge in the bulk and on the surface of the oxide layer of a MOS transistor has been developed. The model takes into account the generation of point defects under fast neutron irradiation. The volume and surface charges obtained by the numerical modeling have been used to calculate the drain—gate characteristic of the MOS transistor exposed to neutron irradiation in different doses and accompanying high-energy gamma-ray irradiation. To model the effect of neutron irradiation, different methods for estimating the rate of point defect generation in a two-component material (SiO2) have been developed. The simulated drain—gate characteristic is shown to agree well with the experimental data obtained at the concentration of hole traps and their capture cross sections lying within the published data for an unirradiated device after exposure to gamma rays from a 60Co gamma source and after irradiation with fast neutrons with an average energy of ∼1 MeV and accompanying gamma rays using a pool-type reactor.     

Synergistic effects of neutron and gamma ray irradiation of commercial CHMOS microcontroller

This paper presents the experimental results of a combined irradiation environment of neutron and gamma rays on 80C196KC20, which is a 16-bit high performance member of the MCS96 microcontroller family. The electrical and functional tests were made in three irradiation environments: neutron, gamma rays, combined irradiation of neutron and gamma rays. The experimental results show that the neutron irradiation can affect the total ionizing dose behaviour. Compared with the single radiation environment, the microcontroller exhibits considerably more severe degradation in neutron and gamma ray synergistic irradiation. This phenomenon may cause a significant hardness assurance problem.     

不同顺序中子/γ辐照对双极器件电流增益的影响

利用CFBR-Ⅱ快中子反应堆(中国第二座快中子脉冲堆)和60Co装置开展不同顺序的中子/γ辐照双极晶体管的实验。在集电极-发射极电压恒定条件下,测量了双极晶体管电流增益随集电极电流的变化曲线,研究不同顺序中子/γ辐照对双极晶体管电流增益的影响。分析实验结果发现,集电极-发射极电压一定时,集电极电流极低情况下电流增益退化比较大,随集电极电流增加电流增益逐渐减小;就实验选中的两类晶体管而言,先中子后γ辐照造成双极晶体管电流增益的退化程度大于先γ后中子辐照,而且PNP型晶体管比NPN型晶体管差异更明显。本文进行了双极晶体管电离/位移协同辐照效应相关机理的初步探讨。     

Synergistic effects of neutron and gamma ray irradiation of a commercial CHMOS microcontroller

This paper presents the experimental results of a combined irradiation environment of neutron and gamma rays on 80C196KC20,which is a 16-bit high performance member of the MCS96 microcontroller family.The electrical and functional tests were made in three irradiation environments:neutron,gamma rays,combined irradiation of neutron and gamma rays.The experimental results show that the neutron irradiation can affect the total ionizing dose behaviour.Compared with the single radiation environment,the microcontroller exhibits considerably more severe degradation in neutron and gamma ray synergistic irradiation.This phenomenon may cause a significant hardness assurance problem.     

The superconducting transition temperature of niobium carbide single crystals after implantation of light elements

This overview outlines some basic properties of defects in insulators and describes experimental techniques by which these defects may be characterized. Then the production of defects by various types of particle irradiation is discussed. Finally some discussion is presented of the potential device application of defective crystals, including tunable colour centre lasers, miniaturised optical circuitry and neutron dosimetry.     

质子与中子辐照对电荷耦合器件暗信号参数的影响及其效应分析

对科学级电荷耦合器件(charge-coupled device, CCD)进行了质子和中子辐照试验及退火试验, 应用蒙特卡洛方法计算了质子和中子在CCD中的能量沉积, 分析了器件的辐射损伤机理. 仿真计算了N⁺埋层内沉积的位移损伤剂量, 辐照与退火试验过程中主要考察暗信号的变化规律. 研究结果显示, 质子与中子辐照均会引发暗信号退化, 其退化的规律与位移损伤剂量变化一致; 退火后, 质子辐照所致CCD暗信号大幅度恢复, 其体暗信号增加量占总暗信号增加量的比例最多为22%; 中子辐照引发的暗信号增长主要为体暗信号. 质子和中子在N⁺埋层产生相同位移损伤剂量的情况下, 两者导致的体暗信号增长量相同, 质子与中子辐照产生的体缺陷对体暗信号增长的贡献是同质的.     

Photoluminescence enhancement from the defects state formed by neutron/gamma mixed irradiation in an epoxy resin for LED applications

ABSTRACT

In the framework of the ICERR (International CEntres based on Research Reactors) project, the effect of neutron/gamma irradiation on material has been studied. In this work, we investigate the mixed neutron/gamma irradiation effects on the optical properties of epoxy resin polymers. Photoluminescence (PL) measurements are used in epoxy resin films irradiated in the dose range from 0 to 900?Gy. For more information about the carriers dynamics, we studied their activation energy and phononic processes through the analysis of the PL spectrum evolution as a function of temperature. Mostly, materials irradiation studies by ionizing sources show a generation of defects and subsequently lead to the damage and degradation on the different properties. In this study we have shown an advantage of neutron/gamma irradiation, it is the improvement of the luminescence properties. The 500?Gy dose has the highest quantum yield at low temperature. But the 600?Gy dose shows the highest yield at room temperature. For the 500?Gy dose, the neutron/gamma treatment mainly favored the activation of carriers from lower to higher levels. On the other side with the 600?Gy dose, there was a combination between the activation of carriers from lower to higher levels and the ionization of trapped electrons in the defects centers.     

一种低活化铁素体/马氏体钢的高能重离子辐照效应研究

低活化的铁素体/马氏体钢是先进核能装置（如聚变堆）的重要候选结构材料。 在聚变堆实际工作环境下, 由于高温和高氦产生率引起的材料失效是这类材料面临的一个重要问题。 本项研究以兰州重离子加速器（HIRFL）提供的中能惰性气体离子束（20Ne, 122 MeV）作为模拟辐照条件, 借助透射电子显微镜, 研究了一种低活化的9Cr铁素体/马氏体钢（T92B）组织结构的变化和辐照肿胀。 实验结果表明, 高温下当材料中晶格原子的撞出损伤和惰性气体原子沉积浓度超过一定限值时, 材料内部形成高浓度的空洞, 并且空洞肿胀率显著依赖于辐照温度和剂量; 在马氏体板条界面及其它晶界处空洞趋于优先形成, 并且在晶界交汇处呈加速生长。 基于氦泡的形核生长与空洞肿胀的经典模型探讨了在不同辐照条件（He离子、 Ne离子、 Fe/He离子双束、 快中子、 Ni离子）下铁素体/马氏体钢中肿胀率数据的关联。Low activation Ferritic/Martensitic steels are a kind of important structural materials candidate to the application in advanced nuclear energy systems. Possible degradation of properties and even failure in the condition of high temperature and high helium production due to energetic neutron irradiation in a fusion reactor is a major concern with the application of this kind of materials. In the present work microstructural evolution in a 9Cr Ferritic/Martensitic steel (T92B) irradiated with 122 MeV 20Ne ions at temperatures between 0.3—0.5 Tm (Tm is the melting point of the material) was investigated with transmission electron microscopy. High concentration voids were observed in the specimens irradiated at high temperatures when the displacement damage dose and Ne concentration exceed a certain level. Preferential formation of voids at lath boundaries and other grain boundaries was found. The data of void swellings in 9Cr ferritic/martensitic steels irradiated in different conditions (such as with He ions, Ne ions, Fe/He dual beams, fast neutrons, Ni ions etc.) were compiled and analyzed based on a classic model of helium bubble formation, and bubble to void transition.     

Hydrogen Release and Room Temperature Creep for Vanadium Alloys Containing Hydrogen

Vanadium alloy has been taken as one of the candidate structural materials for fusion reactors because of its excellent high-temperature mecha nical performances, high thermal stress factor and low radioactivity. It is a kind of potential materials for hydrogen storage as well. Because operated in an environment conta!ning hydrogen and its isotopes or the neutron irradiation resulting transmutation product of H, the problem that H induced degradation of mechanical properties and hydrogen embrittlement has been being one of the key issues for the application for vanadium alloys.     

Helium-hydrogen synergistic effects on swelling in in-situ multiple-ion beams irradiated steels

The development of reliable fusion energy is one of the most important challenges in this century. The accelerated degradation of structural materials in fusion reactors caused by neutron irradiation would cause severe problems. Due to the lack of suitable fusion neutron testing facilities, we have to rely on ion irradiation experiments to test candidate materials in fusion reactors. Moreover, fusion neutron irradiation effects are accompanied by the simultaneous transmutation production of helium and hydrogen. One important method to study the He-H synergistic effects in materials is multiple simultaneous ion beams (MSIB) irradiation that has been studied for decades. To date, there is no convincing conclusion on these He-H synergistic effects among these experiments. Recently, a multiple ion beam in-situ transmission electron microscopy (TEM) analysis facility was developed in Xiamen University (XIAMEN facility), which is the first triple beam system and the only in-running in-situ irradiation facility with TEM in China. In this work, we conducted the first high-temperature triple simultaneous ion beams irradiation experiment with TEM observation using the XIAMEN facility. The responses to in-situ triple-ion beams irradiation in austenitic steel 304L SS and ferritic/martensitic steel CLF-1 were studied and compared with the results in dual- and single-ion beam(s) irradiated steels. Synergistic effects were observed in MSIB irradiated steels. Helium was found to be critical for cavity formation, while hydrogen has strong synergistic effect on increasing swelling.     

Influence of neutron irradiation on etching of SiC in KOH

The effect of reactor neutron irradiation on the etch rate of SiC in potassium hydroxide has been studied. In the case of high irradiation doses (10¹⁹–10²¹ cm^–2), the etch rate of silicon carbide has been shown to drastically rise, especially in the [0001]Si direction. This considerably mitigates the orientation anisotropy of polar face etching. After high-temperature annealing (up to 1200–1400°C), a higher etch rate of irradiated crystals persists. The results have been explained by the high concentration of radiation-induced (partially clustered) defects they contain.

     

利用Si–PIN探测器测量DPF装置中子产额

介绍了Si-PIN中子探测器的结构和测量原理,分析了探测器对14MeV中子的灵敏度.利用该探测器测量了等离子焦点装置的D-T脉冲中子产额,实验结果与SDIN500探测器测量结果在5?%不确定度范围内一致     

Dynamic modeling of total ionizing dose-induced threshold voltage shifts in MOS devices

The total ionizing dose (TID) effect is a key cause for the degradation/failure of semiconductor device performance under energetic-particle irradiation. We developed a dynamic model of mobile particles and defects by solving the rate equations and Poisson's equation simultaneously, to understand threshold voltage shifts induced by TID in silicon-based metal-oxide-semiconductor (MOS) devices. The calculated charged defect distribution and corresponding electric field under different TIDs are consistent with experiments. TID changes the electric field at the Si/SiO₂ interface by inducing the accumulation of oxide charged defects nearby, thus shifting the threshold voltage accordingly. With increasing TID, the oxide charged defects increase to saturation, and the electric field increases following the universal 2/3 power law. Through analyzing the influence of TID on the interfacial electric field by different factors, we recommend that the radiation-hardened performance of devices can be improved by choosing a thin oxide layer with high permittivity and under high gate voltages.     

光电耦合器的反应堆中子辐射效应

 选择3种典型光电耦合器开展了反应堆中子辐照实验,中子注量为3×10¹¹~5×10¹²cm^-2时,位移效应导致电流传输比下降,饱和压降提高。发光器件相同,探测器为Si PIN光电二极管的光电耦合器比探测器为Si NPN光敏晶体管的光电耦合器的初始电流传输比要小,但其抗位移损伤能力更强。探测器均为Si NPN光敏晶体管,发光器件为异质结LED要比硅两性掺杂LED的光电耦合器的电流传输比抗位移损伤能力提高2个量级;以光敏晶体管为探测器的光电耦合器,在较大的正向电流和输出负载电阻条件下工作可提高抗辐射水平。此外,光电耦合器的位移损伤存在加电退火效应。