增强型Cascode结构氮化镓功率器件的高能质子辐射效应研究

针对增强型共栅共源(Cascode)级联结构和耗尽型AlGaN/GaN功率器件,利用60 MeV能量质子开展辐射效应研究.获得了经质子辐照后器件电学性能的退化规律,并与常规耗尽型HEMTs器件辐照后的电学性能进行了比较,发现增强型Cascode结构器件对质子辐照更加敏感,分析认为级联硅基MOS管的存在是其对质子辐照敏感的主要原因.质子辐照使硅基MOS管栅氧化层产生大量净的正电荷,诱导发生电离损伤效应,使其出现阈值电压负向漂移及栅泄漏电流增大等现象.利用等效(60 MeV能量质子,累积注量1×10¹² p/cm²)剂量的⁶⁰Co γ射线辐射器件得到电离损伤效应结果,发现器件的电学性能退化规律与60 MeV能量质子辐照后的退化规律一致.通过蒙特卡罗模拟得到质子入射在Cascode型器件内诱导产生的电离能损和非电离能损,模拟结果表明电离能损是导致器件性能退化的主要原因.     

CuCrZr合金质子辐照效应的模拟研究

基于Monte Carlo方法,跟踪一大批入射粒子的运动,模拟1~10 Me V质子辐照下质子与CuCrZr合金的相互作用,计算出合金的阻止本领、能量传递、能量损失、射程、空位分布情况以及合金的辐照损伤分别与辐照深度、质子能量的关系,通过模拟CuCrZr合金在聚变反应中的工作环境,分析热沉材料的失效机理.研究结果表明:质子能量在1~10 Me V时,质子与CuCrZr合金发生非弹性碰撞,能量损失以电离能损失为主,表现出很好的抗辐照性能;质子在合金中的峰值深度随质子能量增加而增加,且近似指数关系,峰值深度为2~250μm;入射质子能量达到Me V级别时,溅射产额为零,CuCrZr合金可以很好的避免器壁的侵蚀;合金中空位的个数与入射质子能量呈线性关系,合金中空位和质子在合金中的分布具有同步性;质子损伤效率在合金深度方向呈现高斯分布,损伤最大值位置与辐照深度接近,随着入射质子能量的增加损伤效率最大值不断减小.     

质子入射AlxGa1–xN材料的位移损伤模拟

氮化镓材料由于优良的电学特性以及耐辐照性能,其与不同含量Al_xGa_1–xN材料组成的电子器件,有望应用于未来空间电子系统中.然而目前关于氮化镓位移损伤机理研究多关注于氮化镓材料,对于Al_xGa_1–xN材料位移损伤研究较少.本文通过两体碰撞近似理论模拟了10 keV—300 MeV质子在不同Al元素含量的Al_xGa_1–xN材料中的位移损伤机理.结果表明质子在Al_xGa_1–xN材料中产生的非电离能损随质子能量增大而下降,当质子能量低于40 MeV时,非电离能损随着Al含量的增大而变大,当质子能量升高时该趋势相反;分析由质子导致的初级撞出原子以及非电离能量沉积,发现不同Al_xGa_1–xN材料初级撞出原子能谱虽然相似,然而Al元素含量越高,由弹性碰撞产生的自身初级撞出原子比例越高;对于质子在不同深度造成的非电离能量沉积,弹性碰撞导致的能量沉积在径迹末端最大,而非弹性碰撞导致的能...     

近地轨道质子和α粒子入射InP产生的位移损伤模拟

磷化铟(InP)材料具有禁带宽度大、电子迁移率高、耐高温、抗辐照等优点,是制备航天器电子器件的优良材料.近地轨道内的质子和α粒子对近地卫星威胁巨大,其在InP电子器件中产生的位移损失效应是导致InP电子器件电学性能下降的主要因素.本文使用蒙特卡罗软件Geant4研究近地轨道的质子与α粒子分别经过150μm二氧化硅和2.54 mm铝层屏蔽后,在500/1000/5000μm InP材料中产生的非电离能量损失(non-ionizing energy loss, NIEL)、平均非电离损伤能随深度分布以及年总非电离损伤能.研究发现:低能质子射程短且较易发生非电离反应,入射粒子能谱中低能粒子占比越大,材料厚度越小, NIEL值越大;计算质子和α粒子年总非电离损伤能,质子的年总非电离损伤能占比达98%,表明质子是近地轨道内产生位移损伤的主要因素;α粒子年总非电离损伤能占比小,但其在InP中的NIEL约为质子的2—10倍,应关注α粒子在InP中产生的单粒子位移损伤效应.本文计算为InP材料在空间辐射环境的应用提供了参考依据.     

质子束辐照单层石墨烯的损伤效应

基于石墨烯优异的电学性能,其已被广泛应用于许多工业领域.但由于其带隙为零,一定程度上限制了在电子器件方面更进一步的应用.为了通过离子辐照在石墨烯中引入缺陷并打开带隙,本工作研究了能量为750 keV,1 MeV的质子束对硅衬底单层石墨烯的辐照损伤效应.通过对比辐照前后的石墨烯样品的拉曼光谱发现:I_D/I_G随着入射质子能损的增大而增大,与SRIM程序模拟结果趋势一致;缺陷间平均距离L_D随入射质子能量的增大而增大;缺陷密度n_D随入射质子能量的增大而减小.这表明质子在石墨烯中的损伤效应与三维材料相似.     

CCD质子辐照损伤效应的三维蒙特卡罗模拟

针对空间质子诱发CCD性能退化问题,开展了CCD质子辐照效应的三维蒙特卡罗模拟研究。采用三维蒙特卡罗软件Geant4模拟计算了不同能量质子在Si和SiO₂中的射程及Bragg峰,分析了不同能量质子在材料中能量沉积的过程,并将模拟结果与相关数据进行对比,模拟误差在5%以内。根据质子与材料相互作用的物理过程,选取了合适的Lindhard分离函数,添加合适的物理过程,模拟计算了不同能量质子在SiO₂中的电离能量损失和Si中的非电离能量损失,并将结果与国外相关数据进行对比。根据CCD的生产工艺参数,建立了单个像元的三维模拟模型,确定了质子辐照损伤的灵敏体积,模拟计算了不同能量质子在像元灵敏体积内的电离能量沉积与非电离能量沉积,分析了CCD不同能量质子的辐照损伤差异产生的机理。结合粒子输运计算结果与CCD质子辐照实验结果,分析了质子辐照诱发CCD辐射敏感参数退化的物理机制。     

GaInP/GaAs/Ge三结太阳电池不同能量质子辐照损伤模拟

以GaInP/GaAs/Ge三结太阳电池为研究对象,开展了能量为0.7, 1, 3, 5, 10 MeV的质子辐照损伤模拟研究,建立了三结太阳电池结构模型和不同能量质子辐照模型,获得了不同质子辐照条件下的I-V曲线,光谱响应曲线,结合已有实验结果验证了本文模拟结果,分析了三结太阳电池短路电流、开路电压、最大功率、光谱响应随质子能量的变化规律,利用不同辐照条件下三结太阳电池最大输出功率退化结果,拟合得到了三结太阳电池最大输出功率随位移损伤剂量的退化曲线.研究结果表明,质子辐照会在三结太阳电池中引入位移损伤缺陷,使得少数载流子扩散长度退化幅度随质子能量的减小而增大,从而导致三结太阳电池相关电学参数的退化随质子能量的减小而增大.相同辐照条件下,中电池光谱响应退化幅度远大于顶电池光谱响应退化幅度,中电池抗辐照性能较差,同时中电池长波范围内光谱响应的退化幅度比短波范围更大,表明中电池相关电学参数的退化主要来源于基区损伤.     

质子在碳化硅中不同深度的非电离能量损失

利用蒙特卡罗方法,应用Geant4程序,模拟计算了1—500 MeV质子在碳化硅材料中的非电离能量损失,并研究了不同种类的初级反冲原子对非电离能量损失的贡献.模拟结果表明:在相同质子辐照下,碳化硅材料中的非电离能量损失要比硅、镓等半导体材料更小,说明碳化硅器件的稳定性更好,抗位移损伤能力更强;当靶材料足够厚时,在不同能量质子辐照下,材料损伤最严重的区域会随着质子入射能量的增加从质子射程末端逐渐前移到材料表面;不同种类的初级反冲原子对非电离能量损失的贡献表明,在低能质子辐照下,28Si和~(12)C是位移损伤的主要原因,而随着质子能量的增加,通过核反应等过程产生的次级离子迅速增多,并对材料浅层造成严重的位移损伤.     

低能质子辐照对ZnO白漆光学性能退化的影响

 通过光致荧光光谱解谱和X射线光电子能谱（XPS）分析,研究了ZnO白漆经受能量低于200 keV低能质子辐照过程中氧空位缺陷的形成与演化过程。XPS解析表明质子辐照后晶格氧减少,光致荧光光谱解析表明锌空位减少,说明ZnO白漆中氧空位数量增加,且双电离氧空位能够捕获价带中的电子转变为单电离氧空位,使单电离氧空位逐渐成为辐照产生的主要缺陷。质子辐照使ZnO白漆中氧空位数量增加,而氧空位易捕获电子形成色心,从而导致光学性能下降。     

质子辐照作用下浮栅单元的数据翻转及错误退火

本文利用60 MeV质子束流,开展了NAND (not and) flash存储器的质子辐照实验,获取了浮栅单元的单粒子翻转截面,分析了浮栅单元错误的退火规律,研究了质子辐照对浮栅单元的数据保存能力的影响.实验结果表明,浮栅单元单粒子翻转截面随质子能量的升高而增大,随质子注量的升高而减小.浮栅单元错误随着退火时间的推移持续增多,该效应在低能量质子入射时更为明显.经质子辐照后,浮栅单元的数据保存能力有明显的退化.分析认为高能质子通过与靶原子的核反应,间接电离导致浮栅单元发生单粒子翻转,翻转截面与质子注量的相关性是因为浮栅单元单粒子敏感性的差异.质子引起的非电离损伤会在隧穿氧化层形成部分永久性的缺陷损伤,产生可以泄漏浮栅电子的多辅助陷阱导电通道,导致浮栅单元错误增多及数据保存能力退化.     

First-principles calculations of F-, Cl-, and N-related defects of amorphous SiO_2 and their impacts on carrier trapping and proton release

The first-principles calculations based on density functional theory are performed to study F-,Cl-,and N-related defects of amorphous SiO2(a-SiO2) and their impacts on carrier trapping and proton release.The possible geometric configurations of the impurity-related defects,the formation energies,the hole or electron trapping of the neutral defects,and the mechanisms to suppress proton diffusion by doping N are investigated.It is demonstrated by the calculations that the impurity atoms can interact with the oxygen vacancies and result in impurity-related defects.The reactions can be utilized to saturate oxygen vacancies that will cause ionization damage to the semiconducting devices.Moreover,the calculated formation energy indicates that the F-or Cl-related oxygen vacancy defect is a deep hole trap,which can trap holes and prevent them from diffusing to the a-SiO2/Si interface.However,three N-related defects,namely N(2)o-H,N(2)o=O,and N(3)o-Vo,tend to act as shallow hole traps to facilitate hole transportation during device operation.The N(2)o and N(3)o configurations can be negatively charged as deep electron traps during the oxide charge buildup after ionization radiation.In addition,the nudged elastic band(NEB) calculations show that four N-related defects,namely N(2)o,N(2)o-H,N(2)o=O,and N(3)o are capable of capturing protons and preventing them from diffusing to and de-passivating the interface.This research reveals the fundamental properties of the F-,Cl-,and N-related defects in amorphous silica and the details of the reactions of the carrier trapping and proton release.The findings help to understand the microscopic mechanisms that alleviate ionization damage of semiconducting devices by doping a-SiO2.     

Radiation effects of 50-MeV protons on PNP bipolar junction transistors

The effects of radiation on 3CG110 PNP bipolar junction transistors (BJTs) are characterized using 50-MeV protons, 40-MeV Si ions, and 1-MeV electrons. In this paper, electrical characteristics and deep level transient spectroscopy (DLTS) are utilized to analyze radiation defects induced by ionization and displacement damage. The experimental results show a degradation of the current gain and an increase in the types of radiation defect with increasing fluences of 50-MeV protons. Moreover, by comparing the types of damage caused by different radiation sources, the characteristics of the radiation defects induced by irradiation show that 50-MeV proton irradiation can produce both ionization and displacement defects in the 3CG110 PNP BJTs, in contrast to 40-MeV Si ions, which mainly generate displacement defects, and 1-MeV electrons, which mainly produce ionization defects. This work provides direct evidence of a synergistic effect between the ionization and displacement defects caused in PNP BJTs by 50-MeV protons.     

质子辐照对国产“一”字型保偏光纤损伤效应研究

航天器在空间环境中运行时,会受到质子的辐照,光纤环作为航天器上光纤陀螺的重要组成部件受辐照影响 最为严重.为了研究国产“一”字型保偏光纤因质子辐照导致辐照诱导损耗的变化规律及其辐照损伤机理, 选择质子能量为5 MeV和10 MeV,光源波长为1310 nm,原位测量了光纤传输功率变化情况,计算出辐照诱导损耗. 利用SRIM软件,模拟能量分别为5 MeV和10 MeV质子辐照在光纤中的电离和位移损伤分布.借助X 射线光电子能谱仪分析辐照前后O 1s和Si 2p解析谱,借助傅里叶变换红外光谱仪观察光纤辐照前后光谱变化情况研究发现,在波长为1310 nm处, 光纤的辐照诱导损耗随着质子注量的增加而增长,主要原因是由于光纤纤芯中Si-OH的浓度增加所导致. 而且能量为5 MeV质子辐照造成光纤的辐照诱导损耗比10 MeV严重,这是因为5 MeV质子在光纤纤芯处造成的 位移和电离损伤均比10 MeV严重,即产生的Si-OH数量多.     

Atomistic simulations to characterize the influence of applied strain and PKA energy on radiation damage evolution in pure aluminum

Knowledge of defects generation, their mobility, growth rate, and spatial distribution is the cornerstone for understanding the surface and structural evolution of a material used under irradiation conditions. In this study, molecular dynamics simulations were used to investigate the coupled effect of primary knock-on atom (PKA) energy and applied strain (uniaxial and hydrostatic) fields on primary radiation damage evolution in pure aluminum. Cascade damage simulations were carried out for PKA energy ranging between 1 and 20 keV and for applied strain values ranging between ?2% and 2% at the fixed temperature of 300 K. Simulation results showed that as the atomic displacement cascade proceeds under uniaxial and hydrostatic strains, the peak and surviving number of Frenkel point defects increases with increasing tension; however, these increments were more prominent under larger volume changing deformations (hydrostatic strain). The percentage fraction of point defects that aggregate into clusters increases under tension conditions; compared to the reference conditions with no strain, these increases are around 13% and 7% for interstitials and vacancies, respectively (under 2% uniaxial strain), and 19% and 11% for interstitials and vacancies, respectively (under 2% hydrostatic strain). Clusters formed of vacancies and interstitials were both larger under tensile strain conditions, with increases in both the average and maximum cluster sizes. The rate of increase/decrease in the number of Frenkel pairs, their clustering, and their size distributions under expansion/compression strain conditions were higher for higher PKA energies. Overall, the present results suggest that strain effects should be considered carefully in radiation damage environments, specifically for conditions of low temperature and high radiation energy. Compressive strain conditions could be beneficial for materials used in nuclear reactor power systems.     

质子辐射下互补金属氧化物半导体有源像素传感器暗信号退化机理研究

对某国产0.5 μm工艺制造的互补金属氧化物半导体有源像素传感器进行了10 MeV质子辐射试验, 当辐射注量达到预定注量点时, 采用离线的测试方法, 定量测试了器件暗信号的变化情况. 试验结果表明, 随着辐射注量的增加暗信号迅速增大. 采用MULASSIS (multi-layered shielding simulation software)软件计算了电离损伤剂量和位移损伤剂量, 在与γ辐射试验数据对比的基础上, 结合器件结构和工艺参数, 建立了分离质子辐射引起的电离效应和位移效应理论模型, 深入分析了器件暗信号的退化机理. 研究结果表明, 对该国产器件而言, 电离效应导致的表面暗信号和位移效应导致的体暗信号对整个器件暗信号退化的贡献大致相当.     

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.     

Effect of recoil atoms on radiation-defect formation in semiconductors under 1–10-MeV proton irradiation

The formation of radiation defects in Si under 1–10-MeV proton bombardment is analyzed. Numerical simulation is carried out, and histograms of the distribution of the energy transferred to recoil atoms are obtained. Two energy ranges are considered when analyzing the histograms. Single Frenkel pairs with closely located components are produced in the first range (small energies). Recoil atoms of the second range have an energy sufficient for the production of a displacement cascade. As a result, nanoscale regions with high densities of vacancies and different types of their complexes appear. In addition, as the energy of the primary knocked-out atoms increases, the average distance between genetically related Frenkel pairs increases, and, as a consequence, the fraction of pairs that are not recombined under bombardment increases.     

100 keV质子辐照对空间GaAs/Ge太阳电池光电效应的影响

利用空间环境模拟设备,用固定能量为100keV、注量为1×10⁹—3×10¹²cm^-2的质子,对空间实用GaAs/Ge太阳电池进行了辐照试验.利用伏安(I-V)特性、光谱响应和光致发光(PL)光谱测试,研究分析了电池的光电效应.试验表明,电池的各种电性能参数如短路电流(I_sc)、开路电压(V_oc)、最大输出功率(P_{m< 关键词： GaAs/Ge太阳电池 质子辐照 光电效应}