6H-SiC JFET 输出特性及其中子辐照模型

基于沟道调效应、串联电阻效应的考虑,首先建立了一个和实验室符合很好的６Ｈ－ＳｉＣＪＦＥＴ的模型,在该模型中采用了两种电离杂质模型和Ｃａｕｇｈｅｙ－Ｔｈｏｍａｓ方程,接着在分析中子辐照对ＳｉＣ ＪＦＥＴ电参数如电子浓度、迁移率、电阻率和空间电荷区密度影响的基础上,对ＳｉＣ ＪＦＥＴ在室温和３００℃时的辐照响应进行了模拟。模拟结果和实验相符。     

高能Ar离子辐照单晶Si引起的损伤研究

用１１２ＭｅＶ Ａｒ离子以５０Ｋ的低温辐照了〈１１１〉取向的单晶Ｓｉ后在室温下采用Ｘ射线光电子谱（ＸＲＳ）、电子顺磁共振（ＥＰＲ）和红外光吸收（ＩＲ）技术对样品进行了分析。ＸＰＳ分析结果表明，表面处Ｓｉ以单元素和ＳｉＯ２两种形式共存，辐照对这两种形式Ｓｉ的２ｐ轨道电子的结合能影响较小。ＥＰＲ测量结果显示，Ｓｉ中的损伤产生明显地依赖于辐照剂量，当剂量为１．０×１０＾１４－１．８×１０＾１４ｃｍ＾－２     

不同工艺生成的Si—SiO2经电离辐照的电子自旋共振研究

采用电子自旋共振（ＥＳＲ）分析技术，较系统地研究了Ｓｉ－ＳｉＯ２体系中点缺陷Ｐｂ和Ｅ＇随氧化工艺、＾６０Ｃｏγ射线辐照剂量和辐照所加偏压的变化关系。实验结果表明：两类Ｓｉ／ＳｉＯ２样品在γ辐照前后均能观察到Ｐｂ缺陷，且γ辐照在Ｓｉ－ＳｉＯ２中产生更多的Ｐｂ缺陷；第一类样品在正电场下辐照将产生Ｅ＇缺陷，在自由场下辐照剂量达５×１０＾４Ｇｙ（Ｓｉ）时才能观察到Ｅ＇缺陷；在辐照后的第二类样品中无Ｅ＇信号     

He—jet带传输及X—γ（t）符合测量装置和^153Er（EC＋β^＋）衰变新γ的测定

介绍了Ｈｅ－ｊｅｔ带传输及Ｘ－γ（ｔ）符合测量装置分离鉴别重缺中子远离核的原理、速度和效率、离线测试了其最佳工作条件；利用该装置在线测量了＾１９５，１９６Ｂｉ、＾１５２，１５４Ｅｒ和＾１５３Ｅｒ的（ＥＣ＋β＾＋）衰变。６条新γ射线被确定Ｅｒ。     

高纯硅辐射损伤的正电子湮没和扰动角关联研究

采用正电子湮没和扰动角关联方法研究了１．４５×１０２０、３．１０×１０１７ｎ／ｃｍ２中子辐照和５×１０１１／ｃｍ２１７８Ｗ重离子辐照单晶硅引起的辐射损伤及其退火效应。实验测量的正电子湮没寿命和四极相互作用频率表明在Ｓｉ中存在氧一单空位对．高中子剂量和重离子辐照Ｓｉ后，用两种方法都观察到了双空位复合成四空位。     

Si—SiO2及其在电离辐照下的等离激元

用ＸＰＳ分析技术对抗辐射加固与非加固的Ｓｉ－ＳｉＯ２进行了电离辐照前后Ｓｉ的一级等离激元（定位于Ｂ．Ｅ．１１６．９５ｅＶ）及ＳｉＯ２一级等离激元（定位于Ｂ．Ｅ．１２２．０ｅＶ）的研究。实验结果表明：存在一个由这两种等离激元组成的界面，在电离辐射的作用下，此界面区向ＳｉＯ２表面方向展宽，界面中心向ＳｉＯ２表面方向移动；两种Ｓｉ－ＳｉＯ２界面区中的ＳｉＯ２一级等离激元的浓度在正电场中辐照均随辐照剂量的增加而增加，而非加固样品中一级等离激元浓度在正电场中随辐照剂量的变化所产生的变动快于加固样品；在同一辐照剂量下加正电样品中等离激元浓度的变化远明显于不加电样品。     

辽宁－吉林东部地区超镁铁质岩包体的微量元素地球化学特征

发展了预浓集中子活化分析方法，结合仪器中子活化分析对辽宁—吉林东部地区新生代火山岩中尖晶石二辉橄榄岩包体的稀土元素（ＲＥＥ）及其他微量元素进行了测定。它们的过渡金属元素中不相容元素Ｔｉ以及适度相容元素Ｖ和Ｓｃ相对于原始地慢（ＰＭ）均具亏损的特征；而相容元素Ｃｏ、Ｎｉ和Ｃｒ含量略高或类似于ＰＭ，反映了它们应为经历了部分熔融后的残余地幔。依据ＲＥＥ特征尖晶石二辉橄榄岩可分为两类：第一类包体的ＲＥＥ含量和ＲＥＥ分配型式与ＰＭ相比呈现明显的亏损，提供了它们是残余地慢岩的又一证据。第二类包体的重稀土元素（ＨＲＥＥ）比前者低，但轻稀土元素（ＬＲＥＥ）比前者明显的高，揭示了它们在地幔源岩经历了部分熔融，使ＲＥＥ发生了亏损之后又遭受了ＬＲＥＥ富集，即地幔交代作用。     

30MeV／u^40Ar＋159Tb反应中用于中等质量碎片测量的BGO阵列探测器

报道３０ＭｅＶ／ｕ＾４０Ａｒ＋１５０Ｔｂ反应中用于中等质量碎片（Ｚ≥３）测量的△Ｅ（Ｓｉ）＋Ｅ（ＢＧＯ）望远镜阵列的测试结果，实验表明该探测器阵列中等质量碎片有较好的粒子鉴别能力。     

P沟MOSFET／FIPOS的γ射线总剂量辐照特性

采用高选择和自终止多孔氧化硅全隔离技术的制备了高质量的ＳＯＩ材料，研究了在该材料上采用２μｍＣＭＯＳ工艺制备的不同沟道长度的Ｐ沟ＭＯＳＦＥＴ的＾６０Ｃｏγ射线总剂量辐照特性，表明经５ｋＧｙ（Ｓｉ）辐照后，器件仍有特性，但阈值电压有较大的漂移，这主要是由栅氧化层中的辐照感生电荷而引起，不同的沟长度ＰＭＯＳＦＥＴ的辐照特性有基本相同，经一段时间室温退火，阈值电压出现回漂。     

Ar离子辐照的非晶态合金表面发泡扫描电镜观测

１５０、１９５和３００ｋｅＶＡｒ离子在室温下辐照非晶态合金Ｃｏ７０．２Ｆｅ３． ９Ｎｄ３．９Ｓｉ１４Ｂ８和Ｃｏ６６Ｆｅ４．５Ｖ２．２５Ｎｉ２．２５Ｓｉ１０Ｂ１５，扫描电镜在一定的辐照剂量范围观测到了表面发泡形成，发泡形成的临界剂量和直径随离能量增加而增加。Ａｒ离子能量高于１９５ｋｅＶ时，发泡和发泡破裂是主要的表面损伤现象，而在１５０ｋｅＶＡｒ离子辐照下，未观测到发泡破裂。     

Isochronal recovery and damage rate measurements in dilute NiSi alloys

The interaction of Ni-selfinterstitials with Si atoms in dilute NiSi alloys has been investigated by residual resistivity recovery after 5 K low dose electron irradiation and by damage rate measurements in the temperature range of stage II. In stage II the recovery spectra not only show the well known 250 K recovery stage but also a strong recovery peak at 105 K. After annealing to temperatures above 400 K a smaller residual resistivity is found as before irradiation, indicating a Si segregation during the recovery. The damage rates at 86 K show that single Si atoms act as traps for migrating Ni-selfinterstitials. At 105 K the initial damage rate becomes strongly dependent on the Si concentration but trapping at Si is still observed. This behavior as well as the dependence of the recovery from the Si and the defect concentration has been explained by the migration of the Ni-selfinterstitial-Si complexes at 105 K combined with a strong absorption of these migrating complexes at sinks.     

Effect of Injection Level on Carrier Lifetime in Neutron-Irradiated Germanium

The dependence of minority carrier lifetime on injection level was analyzed to yield recombination center parameters for neutron-irradiated germanium. The results are an improvement over data obtained by other methods because they eliminate a possible dependence of capture probability on temperature, and are more sensitive to energy level position. Six n-type specimens doped with arsenic and antimony in the resistivity range from one to twenty ohm-cm were studied. The results reveal a recombination center level of Er - Ev = 0. 34 ± 0.01 eV for antimony-doped germanium and Er - Ev = 0.335 ± 0.01 eV for arsenic-doped germanium. The dependence of lifetime on injection level for high excitation demonstrated the appropriateness of the model which includes the effect of a level of Ec - Er ~ 0.2 eV.     

DyxEr5－xSi3系列化合物晶体结构和磁性研究

利用电弧炉制备了DyxEr5－xSi3（x＝0,1,2,3,4,5）系列化合物样品。通过X射线粉末衍射分析和磁性测量研究了Dy替代Er对Er5Si3化合物晶体结构和磁性的影响。结果表明：DyxEr5－xSi3（x＝0,1,2,3,4,5）系列化合物的晶体结构为Mn5Si3型,随着Dy替代量的增加,晶胞体积变大。当0≤x≤2时,样品具有反铁磁性,顺磁居里温度由负值（x＝0）变为正值;而x＝3,4时,样品显现铁磁性,顺磁居里温度均为正值。虽然磁性原子及其相互作用的变化对磁性能影响很大,但所有样品的磁有序转变温度都很好地遵守了DeGennes定律。     

Geometric Control of Surface Leakage Current and Noise in Lithium Drifted Silicon Radiation Detectors

Lithium drifted silicon radiation detectors exposed to normal ambient have been shown to have a surface n-type layer which extends from the "n" side over to the " p" side of the device. In this paper a continuation of the study of surface problems is presented, and a successful method for the control of leakage current and noise due to surface breakdown is shown. Noise measurements carried out on Li-drifted silicon devices show clearly the existence of two mechanisms for surface noise generation. One has the characteristics of shot noise, while the second one is much noisier than shot noise. Surface potential measurements correlated with light probe scanning give indication as to the origin of the currents which cause the two types of noise. The measurements also suggest the desirability of increasing the resistivity of the surface layer, and show that this can be attained by increasing the magnitude of the internal fields normal to such surface. One possible way of increasing the magnitude of the fields normal to the exposed junction surface consists in shaping the Si crystal so that, after the Li drifting process has been completed, regions of high fields exist within the compensated region. A comparison of cylindrical, planar, and "inverted T" types of p-i-n devices shows the superiority of the third type of device in that it is possible to apply high bias (between 150 and 200 V/mm at room temperature) before the onset of the high noise mechanism.     

Influence of Impurities on Carrier Removal and Annealing in Neutron-Irradiated Silicon

The influence of impurities on carrier removal and annealing has been investigated in neutron-irradiated silicon in the resistivity range from 0.5 to 50 ohm-cm. Carrier removal rates in n-type material are strongly dependent upon the crystal growth method and are lower in Czochralski-grown (oxygen containing) material than in material grown by the vacuum-float-zone or LOPEX techniques. A slight dependence of the removal rate on the dopant impurity is observed in vacuum-float-zone material but not in Czochralski-grown material. The annealing behavior of n-type material is also very crystal growth dependent. An annealing stage located between approximately 144°C and 170° C is observed in vacuum-float-zone and LOPEX-grown material but not in material grown by the Czochralski method. The location of the stage is dependent upon the dopant impurity. Carrier removal at room temperature in p-type material is not influenced by the growth method or the dopant impurity. However, dopant effects are observed upon annealing.     

Ensuring the possibility of using thorium as a fuel in a pressurized water reactor(PWR)

The possibility of utilizing thorium as a fuel in a pressurized water reactor(PWR)has been proven from the neutronic perspective in our previously published work without assessing the thermal hydraulic(TH)and solid structure performances.Therefore,the TH and solid structure performances must be studied to confirm these results and ensure the possibility of using a thorium-based fuel as an excellent accident-tolerant fuel.The TH and solid structure performances of thorium-based fuels were investigated and compared with those of U02.The radial and axial power peaking factors(PPFs)for U02,(232Th,235U)02,and(232Th,233U)02 were examined with a PWR assembly to determine the total PPF of each one.Both Gd203 and Er203 were tested as burnable absorbers(BAs)to manage the excess reactivity at the beginning of the fuel cycle(BOC)and reduce the total PPF.Er203 resulted in a more significant reduction to the total PPF and,therefore,a greater reduction to the temperature distribution compared to Gd203.Given these results,we analyzed the effects of adding Er203 to thorium-based fuels on their TH and solid structure performances.     

Ion implantation of rare earth ions for light emitters

We discuss the excitation and deexcitation processes for solid state optical emitters. At present, there is considerable interest in depositing a material system, which is compatible to silicon microelectronics processing and which emits electroluminescence (EL). We will compare the EL results of rare earth doped transistors in silicon with doped insulators and doped wide bandgap semiconductors, especially Er in Si (a source for 1.5 μm) as well as Er and Tb in SiO₂, Si₃N₄ and AIN, which are sources for infrared and visible light. The most impressive results are achieved by RE doped GaN film devices, which cover the entire visible spectrum.     

Bias Annealing of Radiation and Bias Induced Positive Charges in N- and P-Type MOS Capacitors

The radiation-induced positive charges trapped in an n-type MDS capacitor were observed to decrease with the number of C-V measurements. The positive gate bias applied on the capacitor was found to cause the decrease in the trapped charges. Its proposed mechanism was a recombination of the trapped positive charges with electrons injected from the Si substrate into the SiO2 layer due to the bias.     

Calorimetry of ion beam damage in silicon

Annealing of ion-beam damage in crystalline Si has been characterized by differential scanning calorimetry and infrared absorption spectroscopy. Si discs of 100 μm thickness have been bombarded with 3.4 MeV protons. Scanning calorimetry reveals a sharp peak riding on a broad background signal. From infrared absorption, this peak is tentatively identified as heat release associated with divacancy annihilation.     

Photoluminescence and radiation effect of Er and Pr implanted silicon-rich silicon oxide thin films

Er and Pr ions were implanted into silicon-rich silicon oxide (SRSO) thin films with Si crystals embedded in SiO₂ matrix. The 525 and 546 nm luminescence peaks were clearly observed in Er-only doped film, but disappeared in the photoluminescence (PL) spectra of Er-Pr codoped films. Instead, a broad PL spectrum extending from 450 to 700 nm was obtained for Er-Pr codoped films with Er/Pr concentration ratio of 1. Concentration profiles of Si, Er and Pr ions in films were simulated by SRIM2006 and related radiation effect on PL response was also discussed. Our results indicate that this material is a potential candidate for the development of white light-emitting diode (LED) and field emission displays for its visible luminescence.