剂量率对MOS器件总剂量辐射性能的影响

对3种MOS器件在不同模拟源的两种辐照剂量率下进行辐照实验,研究了MOSFET阈值电压随辐射剂量及剂量率的变化关系。对实验结果进行了分析讨论。试验表明：在相同辐射剂量下,低剂量率辐照损伤比高剂量率大。     

总剂量辐射对高速电路时间特性的影响

对不同辐照偏置条件下，总剂量辐射对高速CMOS电路54HC04时间参数的影响进行了探讨，并与相应的直流参数的响应特性进行了对比，研究了两者之间的相关性。结果表明，在总剂量辐射环境下，高速CMOS电路的延迟时间变化与阈电压的漂移有着强烈的相关性，0V和4．5V两种偏置状态将分别导致电路的时间参数的明显退化。     

稳态总剂量效应(TID)试验剂量率选择的研究

通过调研分析,发现ESA/SCC 22900和MIL-STD-883G方法1019.7在剂量率的选择等方面存在较大差异。针对美国宇航局NASA发布的TID试验报告中总剂量及其对应的剂量率值进行统计分析,了解到不同工艺器件进行TID试验时采取多步骤辐射,辐射过程中所选择的剂量率几乎均小于1rad(Si)/s,且剂量率随总剂量不断改变。当总剂量低于30krad(Si)时,曲线分布没有规律,随机性较大;当总剂量大于30krad(Si)时,剂量率随总剂量的增加而增加,但不满足线性关系。针对不同剂量率辐射后器件失效机理的分析研究,得出器件在低剂量率辐射下失效的主要原因是界面态,而在高剂量率辐射失效的主要原因是辐射感生氧化物陷阱电荷。     

质子辐照对RADFETs的γ辐照剂量响应的影响研究

针对辐射敏感晶体管(Radiation Sensitive Field-Effect Transistors,RADFETs)在地面标定使用60Co γ射线源而实际空间应用时存在的质子电子辐射环境的差异性问题,进行了10 MeV质子和60Coγ射线的对比辐照与协和辐照试验.采用中带电压法(Mid-gap Techniq...     

γ总剂量辐射对CMOS器件性能的影响

本文比较了相同结构不同工艺的CMOS电路γ电离辐射效应结果。它表明:未经加固的市售器件,对γ总剂量辐射相当灵敏。特别是硅栅器件,正偏置下,大约经15Gy的γ剂量辐射后即告失效;在70Gy下,静态功耗电流增加4.5个量级。从实验结果出发,讨论了CMOS电路γ总剂量电离辐射效应的失效标准和加固方法。     

动态偏置频率对X射线总剂量效应的影响

辐射偏置条件是影响MOSFET(Metal Oxide Silicon Field Effect Transistor)总剂量辐射效应的主要因素之一,因为辐射时栅氧化层中电荷的产生、传输与俘获都与辐射偏置有关.本文采用10 keV X射线对MOSFET在不同频率的动态偏置条件下进行总剂量辐射,分析了MOSFET辐照前后的阈值电压的漂移量和辐射感生电荷对阈值电压的影响.实验结果表明,动态偏置频率越高,辐射对MOSFET电特性的影响越小,产生的辐射感生电荷越少.     

0.35μm部分耗尽SOI NMOSFET的总剂量辐射效应与偏置状态的关系

研究了深亚微米部分耗尽型SOI NMOSFET的抗总剂量辐射特性,主要讨论不同偏置状态对器件抗总剂量辐射性能的影响及其原因。通过器件模拟发现,辐射过程中的不同偏置状态使器件的电场分布差异很大,而器件埋层中俘获空穴的分布与电场密切相关,进而对器件产生不同的影响。模拟结果表明,器件在关态偏置下,背沟道附近陷获电荷密度最高,引起的阈值电压负向漂移和泄漏电流最大,即该偏置状态为浮体器件抗总剂量辐射的最劣偏置状态。     

γ射线辐照对掺Ce钛酸铋铁电薄膜性能的损伤

采用溶胶-凝胶法在复合基底Pt/Ti/SiO₂/Si上制备系列Bi_3.25Ce_0.75Ti₃O₁₂(BCTO)铁电薄膜,并对薄膜进行了不同剂量的γ射线辐照。通过热重-示差扫描量热分析仪(TG-DSC)、X射线衍射仪(XRD)、扫描电子显微镜-能谱仪(SEM-EDS)和铁电测试仪等对辐照前后的薄膜的结构、微观形貌、铁电性、漏电性以及抗疲劳性等进行了对比研究。结果表明：随着对γ射线吸收剂量的增加,薄膜的晶体结构没有改变;薄膜的铁电性能显著减弱,剩余极化2Pr从辐照前的51.5μC/cm²下降到23.7μC/cm²;薄膜的漏电流密度增大,从辐照前的0.9×10^-7 A/cm²增大到7.2×10^-7 A/cm²;在经历10¹²次开关极化循环后,部分薄膜出现疲劳现象。     

过辐照、加速退火及离散性对存储器电参数的影响研究

研究了过辐照和加速退火对存储器TID试验结果的影响,研究结果表明,额外50%剂量辐射和高温100℃168h退火是严格考核空间辐射环境下存储器TID效应的必要试验步骤。分析器件本身的离散性对TID试验结果的影响,提出在辐射前,对器件进行初始数据测试,得出器件参数的标准偏差。通过剔除使标准偏差明显变大的器件,可以减小存储器辐照后的离散性。综述分析了NASA报告中描述的TID试验结果,得出了存储器辐射后进行电参数测试时,读、写、擦模式的综合测试,比只读模式的测试更全面的反应出器件被辐射后的退化特性,并总结出了存储器辐射后电参数测试时应遵循的测试顺序。     

NF-86、NF-87与FWT-60三种辐射变色染料尼龙薄膜剂量计性能的比较研究

NF-86和NF-87两种剂量计均是以尼龙为基质材料,分别以六羟乙基付品红氰化物和付品红氰化物为辐射变色染料的薄膜剂量计。本文给出这两种剂量计与国外同类产品——美国远西公司的FWT-60辐射变色尼龙薄膜剂量计主要剂量学性能比较研究的结果。结果表明NF-86、NF-87剂量计的性能已接近和达到美国FWT-60剂量计的水平,能够为国内辐射加工中γ剂量测量(10~3—10~5Gy)提供一种简便快速而又可靠的监测手段。     

Effects of total-dose irradiation on gate-all-around (GAA) devices

The response of gate-all-around (GAA) MOS transistors to dose irradiation is quite different from that observed on other types of silicon-on-insulator (SOI) MOSFETs. In regular SOI MOSFETs, edge leakage increases substantially faster than the main transistor leakage upon creation of oxide charges due to the irradiation. The GAA MOSFET behaves in the opposite way; the shift of edge threshold voltage upon creation of charges in the oxide is smaller than that of the main transistor. As a result, a kink develops in the subthreshold characteristics of regular SOI MOSFETs upon irradiation, while the original subthreshold kink of GAA devices disappears when the device is irradiated     

Research on total-dose irradiation effect of hardened partially-depleted NMOSFET/SIMOX

In this work, top and back gate characteristics of partially-depleted NMOS transistors with enclosed gate fabricated on SIMOX which is hardened by silicon ions implantation were studied under X-ray total-dose irradiation of three bias conditions. It has been found experimentally that back gate threshold shift and leakage current were greatly reduced during irradiation for hardened transistors, comparing to control ones. It has been confirmed that the improvement of total-dose properties of SOI devices is attributed to the silicon nanocrystals （nanoclusters） in buried oxides introduced by ion implantation.     

CMOS 4000及54HC器件的总剂量辐照响应特性比较

通过对CMOS 4000、54HC系列门电路进行不同偏置条件下的电离辐照实验,比较了电离辐照环境中CMOS 4000和54HC系列电路的总剂量辐照响应特性,对其响应差异进行了较深入的机理研究,并探讨了54HC电路的抗辐射能力测试方法和评判标准.     

Effects of nitrogen on ozone synthesis in packed-bed dielectric barrier discharge

The effects of nitrogen on ozone synthesis are studied in a coaxial cylinder generator with dielectric barrier discharge (DBD) and pack-bed dielectric barrier discharge (PB-DBD). A series of 10 h discharge experiments are conducted adopting a bare stainless electrode and bare copper electrode. Results show that the material of the electrode can affect the ozone synthesis. It is inferred that the ozone zero phenomenon (OZP) may be induced from ozone decomposing by metallic oxide catalysis. Packing dielectric particles can reduce the OZP. Adding a certain amount of nitrogen into the oxygen feed gas can further eliminate the OZP, and increase the ozone concentration significantly, but decreases the maximum energy efficiency of ozone generators. Initial analysis indicates that the optimal proportion of nitrogen addition is inversely related to the average reduced electric field strength in the discharge region.     

Effects of O swift heavy ion irradiation on indium oxide thin films

Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O⁷⁺ ions with different fluences of 5 × 10¹¹, 1 × 10¹² and 1 × 10¹³ ions/cm². X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from ∼78.9 to 43.0 cm²/V s, following irradiation. Films irradiated with a fluence of 5 × 10¹¹ ions/cm² showed a better combination of electrical properties, with a resistivity of 4.57 × 10⁻³ Ω cm, carrier concentration of 2.2 × 10¹⁹ cm⁻³ and mobility of 61.0 cm²/V s. The average transmittance obtained from the as-deposited films decreased from ∼81% to 72%, when irradiated with a fluence of 5 × 10¹¹ ions/cm². The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as “radish-like” morphology when irradiated with a fluence of 5 × 10¹¹ ions/cm².     

Effects of nitrogen ion irradiation on endoglucanase activity and gene mutation of Bacillus subtilis Bac01

Bacillus subtilis Bac01 was mutated by 15 keV N+ ions of 1.5×1016 cm-2.The mutant strain Bacll with high yield of endoglucanase was isolated using carboxymethylcellulose sodium and congo red indicative plates.It exhibited higher endoglucanase activitiy (381.89IU) than the original strain Bac01 (93.33IU).Two 1,500 bp endoglucanase gene fragments were obtained with PCR amplification from B.subtilis Bac01 and mutant strain Bac11.BLAST comparison result indicated that 10 nucleotides mutated.Bioinformatics methods were used to analyze the two predicted amino acid sequences,and it was found that 5 amino acid residues changed,being all in the cellulose-binding domain of endoglucanase.     

Effects of ion irradiation on the structural transformation of sol-gel derived TEOS/MTES thin films

Ion beam processing of organic/inorganic thin films has been shown to be an effective means in converting polymeric films into their final ceramic-like state. In this study, hybrid sol-gel derived thin films based on TEOS (tetraethylorthosilicate) Si(OC₂H₅)₄ and MTES (methyltriethoxysilane) CH₃Si(OC₂H₅)₃ were prepared and deposited on Si substrates by spin coating. After the films were allowed to air dry, they were heat treated at 300 °C for 10 min. Ion irradiation was performed at room temperature using 125 keV H⁺ and 250 keV N²⁺ ions with fluences ranging from 1 × 10¹⁴ to 5 × 10¹⁶ ions/cm². FT-IR and Raman spectroscopies were used to quantify the chemical structural transformations which occurred including the evolution of the organic components, the cross-linking of silica clusters, and the clustering of carbon.     

Effects of energetic heavy ion irradiation on the structure and magnetic properties of FeRh thin films

Fe-54at.%Rh thin films were irradiated with 10 MeV iodine ions at room temperature. Before and after the irradiations, the changes in magnetic properties and the lattice structure of the samples were studied by means of a SQUID magnetometer and X-ray diffraction. For the low fluence irradiation, the SQUID measurement at 20 K shows that the anti-ferromagnetic region of the thin film is changed into ferromagnetic region by the irradiation. As the film thickness is much smaller than the ion range, we can discuss the relationship between the density of energy deposited by ions and the change in magnetization quantitatively. For the high fluence irradiation, the magnetization of the film is strongly decreased by the irradiation, which can be explained as due to the change in lattice structure from B2 into A1 structure by the irradiation.     

Ion-beam irradiation effects on reactively sputtered CrN thin films

The present study deals with CrN/Si bilayers irradiated at room temperature (RT) with 120 keV Ar ions. The CrN layers were deposited by d.c. reactive sputtering on Si(1 0 0) wafers, at different nitrogen partial pressures (2 × 10⁻⁴, 3.5 × 10⁻⁴ and 5 × 10⁻⁴ mbar), to a total thickness of 240-280 nm. The substrates were held at room temperature (RT) or 150 °C during deposition. After deposition the CrN/Si bilayers were irradiated up to fluences of 1 × 10¹⁵ and 1 × 10¹⁶ ions/cm². Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and grazing angle X-ray diffraction (XRD). For the highest nitrogen pressure (5 × 10⁻⁴ mbar) a pure stoichiometric CrN phase was achieved. The results showed that Ar ion irradiation resulted in the variation of the lattice constants, micro-strain and mean grain size of the CrN layers. The observed microstructural changes are due to the formation of the high density damage region in the CrN thin film structure.     

Effect of 4MeV electron beam irradiation on carbon films

Pulsed KrF excimer laser is used to deposit tetrahedral amorphous carbon (ta-C) thin films on Si (1 1 1) single crystal substrates at room temperature under vacuum ∼10⁻⁶ mbars. The pristine deposited films are then irradiated by 4 MeV electron beam at doses varying from 1000 to 4000 cGy. Analysis through AFM illustrates that the irradiation of electron has induced cluster formation on the film surface and increased the surface roughness. Optical properties (n, α and Tauc optical band gap) measured by spectroscopic ellipsometry and electrical resistivity measured by four probe technique are found to depend strongly on electron dose. High electron doses cause significant alteration in order/disorder or sp² states in the film which is the main cause of modifying band gap in the carbon films. The electrical conductivity of the films also increases by increasing electron dose which is due to tunneling of charge carriers through neighbouring conductive chains. The present electron irradiation process at varying electron doses proved to be successful to modulate the optical and electrical properties of carbon films.