电离辐射对部分耗尽绝缘体上硅器件低频噪声特性的影响

本文针对辐射前后部分耗尽结构绝缘体上硅(SOI)器件的电学特性与低频噪声特性开展试验研究. 受辐射诱生埋氧化层固定电荷与界面态的影响, 当辐射总剂量达到1 M rad(Si) (1 rad = 10^-2 Gy)条件下, SOI器件背栅阈值电压从44.72 V 减小至12.88 V、表面电子有效迁移率从473.7 cm²/V·s降低至419.8 cm²/V· s、亚阈斜率从2.47 V/dec增加至3.93 V/dec; 基于辐射前后亚阈斜率及阈值电压的变化, 可提取得到辐射诱生界面态与氧化层固定电荷密度分别为5.33×10¹¹ cm^{- 2}与2.36×10¹² cm^-2. 受辐射在埋氧化层-硅界面处诱生边界陷阱、氧化层固定电荷与界面态的影响, 辐射后埋氧化层-硅界面处电子被陷阱俘获/释放的行为加剧, 造成SOI 器件背栅平带电压噪声功率谱密度由7×10^{- 10} V²·Hz^-1增加至1.8×10^-9 V² ·Hz^-1; 基于载流子数随机涨落模型可提取得到辐射前后SOI器件埋氧化层界面附近缺陷态密度之和约为1.42×10¹⁷ cm^-3·eV^-1和3.66×10¹⁷ cm^-3·eV^-1. 考虑隧穿削弱因子、隧穿距离与时间常数之间关系, 本文计算得到辐射前后埋氧化层内陷阱电荷密度随空间分布的变化.     

Folding Model Analysis of Elastic Scattering of 11B from Light,Medium, and Heavy Nuclei

The elastic scattering angular distributions of ¹¹B projectile on light, medium, and heavy target nuclei including ⁷Li, ⁹Be, ¹²C, ¹⁶O, ^24,25,26Mg, ²⁷Al, ²⁸Si, ⁴⁰Ca, ⁵⁸Ni, ⁵⁹Co, ⁶⁰Ni, ¹⁹⁷Au, ²⁰⁸Pb, and ²⁰⁹Bi have been analyzed at various incident energies. The theoretical results have been obtained by using two different nuclear potentials within the framework of the optical model (OM). Firstly, the double folding potential for real part and the Wood-Saxon (WS) potential for imaginary part have been applied. Secondly, the calculations with double folding potential for both real and imaginary part have been performed and compared with the experimental data. It has been seen that the results are in very good agreement with the experimental data. Also, the volume integrals and cross-sections for each reaction have been obtained. Finally, a new and simple formula for the imaginary potential depth has been derived to clarify the nuclear interactions of ¹¹B nucleus at low energy reactions.     

Gamma decay of K levels

Electromagnetic transition rates between states in ⁴⁰K up to 2.6 MeV excitation were investigated. The reaction ³⁷Cl(, nγ)⁴⁰K was used for lifetime measurements with the DSAM, and the reaction ⁴⁰Ar(p, nγ)⁴⁰K for the derivation of spins and mixing ratios from angular distributions. The transition strengths between states of predominant particle-hole character are well described by a rather simple shell-model structure with empirical effective charges and moments.     

Polarization of neutrons from the O(d, n)F reaction

The polarizations of neutrons from the ¹⁶O(d, n₀)¹⁷F and ¹⁶O(d, n₁ ¹⁷F reactions have been measured at 30° (lab) in steps of approximately 0.15 MeV from E_d = 3.96 to 5.35 MeV. Polarization angular distributions have been obtained at 3.96 and 5.35 MeV. It is determined that the random phase approximation for the scattering amplitudes is not appropriate for the compound nucleus contributions. The analysis indicates probable interference between the compound nucleus and direct interaction reaction mechanisms.     

Nuclear reactions between oxygen isotopes

Elastic and inelastic cross sections have been measured for the system ¹⁶O + ¹⁷O at c.m. energies from 12.5 to 15.5 MeV, and for ¹⁶O + ¹⁸O at c.m. energies from 12 to 20 MeV, at angles between 60° and 125°. Position-sensitive detectors were employed, using the kinematic coincidence technique. The data have been analyzed with particular attention to the contributions of multiple-exchange processes.     

Solid state NMR characterisation of crystalline Na2OZrO2SiO2 phases

The NMR interactions of crystalline phases in the system Na₂O-ZrO₂-SiO₂ have been studied by a combination of static and magic angle spinning NMR methods for the first time. A full multinuclear (¹⁷O, ²³Na, ²⁹Si and ⁹¹Zr) approach has been employed that allows the phases to be clearly identified. NMR interactions such as ²⁹Si isotropic chemical shift correlate with the known structural units present. For ²³Na the different sites can often be distinguished on the basis of differing quadrupolar interactions.     

Electric Multipole Moments for Some First—Row Diatomic Hydride Molecules

As an example of the use of the analytical formulas derived for electric multipole moment integrals over STOs in our previous work(I.I.Guseinov,et al.,J.Mol.Struct(Theochem)465(1999)5),the 2ν-pole electric moments have been calculated for the ground electronic states of LiH,BH and FH of the first-row diatomic hydride molecules,Calculated electric multipole moment values are in agteement with literatures.By the use of these analytical formulas the 2^ν-pole moments for multiatomic molecules can be evaluated most efficiently and accurately by employing STOs as basis sets.     

Hydrogen burning of O in the CNO cycle

The direct capture process in the ¹⁷O(p, γ)¹⁸F reaction has been used to determine the reduced proton widths of the states in ¹⁸F near the proton threshold. The observed upper limits on these widths are up to factors of 60 smaller than the previously assumed values implying a corresponding reduction of the stellar reaction rate for the ¹⁷O(p, )¹⁴N reaction. These results together with results from previous work lead to the conclusion that the CNO cycle is tricycling with the reactions ¹⁷O(p,γ)¹⁸F(β⁺ν)¹⁸O(p, )¹⁵N as the third cycle. The implications of these results on the equilibrium abundances of the elements synthesized in this cycle are discussed.     

Solid-state 17O NMR study of the electric-field-gradient and chemical shielding tensors in polycrystalline gamma-glycine

We report the first experimental determination of the carboxylate oxygen electric-field-gradient (EFG) and chemical shielding (CS) tensors in polycrystalline γ-glycine. Analysis of magic-angle spinning (MAS) and stationary ¹⁷O NMR spectra of [¹⁷O]-γ-glycine obtained at 9.4, 14.1, 16.4, and 18.8 T yields the magnitudes of the ¹⁷O EFG and CS tensors and the relative orientations between the two tensors. Extensive quantum chemical calculations at both the restricted Hartree–Fock and density functional levels have been performed to present the absolute tensor orientations in term of the molecular frame. We have demonstrated that ¹⁷O NMR tensor information could be unambiguously derived by the multiple field analyses of stationary ¹⁷O NMR spectra.     

Incorporation of hydrogen in CdTe and HgTe epitaxial layers grown by MOCVD

The incorporation of hydrogen into MOCVD-grown layers of CdTe, HgTe and CdHgTe using H₂ as the vector gas has been studied. Concentrations of incorporated H going from 6.5 × 10¹⁷ cm^-3 to 5 × 10¹⁸ cm^-3 have been found by SIMS in CdTe layers. This concentration decreases with increasing growth temperature and decreasing bond strength of the host material.     

张量力在16O+16O熔合动力学中的效应（英文）

利用时间相关Hartree-Fock 理论和完整Skyrme 有效相互作用研究了16O+16O 碰撞在库仑位垒附近的熔合动力学。数值计算是在没有任何对称性约束的三维笛卡尔基下完成。将时间相关Hartree-Fock 理论和冻结密度近似下的能量密度泛函方法给出的库仑位垒与实验结果进行了比较,发现同位旋标量的张量项能降低自旋饱和体系16O+16O的库仑位垒,而库仑位垒高度随着同位旋矢量的张量项的耦合常数减小而降低。并计算了包含和不包含张量力的16O+16O熔合截面,发现张量力对16O+16O碰撞在库仑位垒附近的熔合动力学影响较小。The fusion dynamics of 16O+16O around Coulomb barrier has been studied in the timedependent Hartree-Fock (TDHF) theory with the full Skyrme effective interaction. The calculations have been carried out in three-dimensional Cartesian basis without any symmetry restrictions. We have included the full tensor force and all the time-odd terms in Skyrme energy density functional (EDF). The Coulomb barrier obtained from the dynamical TDHF calculations and EDF with frozen density approximation has been compared with the available experimental data. The isoscalar tensor terms and the rearrangement of other terms are found to decrease the barrier height in the spin-saturated system 16O+16O, while the energy of Coulomb barrier tends to decrease as the isovector coupling constant decreases. The fusion cross section for 16O+16O collision has been calculated with and without the tensor force. We found that the tensor force has minor effect on the fusion dynamics of 16O+16O at the energies around Coulomb barrier.     

An ab initio calculation of 17O and 29Si NMR parameters for SiO2 polymorphs

Ab initio molecular orbital calculations (Hartree–Fock, HF and density functional theories, DFTs) have been carried out for SiO₂ polymorphs coesite, low cristobalite, and -quartz, in order to investigate the reliability of this method for predicting ²⁹Si and ¹⁷O nuclear magnetic resonance (NMR) properties of silicates. Oxygen- and silicon-centered clusters consisting of one (1T) to three tetrahedral (3T) shells (one to four atomic shells), taken from real crystal structure, have been investigated. It is found that for reasonable predication of both the ²⁹Si and ¹⁷O chemical shifts (δ_i^Si and δ_i^O), the minimum cluster is one that gives the correct second neighbors to the nucleus of interest. Both the δ_i^Si and δ_i^O have reached convergence with respect to cluster size at the OH-terminated two tetrahedral (2T) shell (three atomic shells around Si and four atomic shells around O) model. At convergence, the calculated δ_i^Si values agree well (within ±1 ppm) with experimental data. The calculated ¹⁷O electric field gradient (EFG)-related parameters also agree with experimental data within experimental uncertainties. The calculation also reproduces small differences in δ_i^O for O sites with similar tetrahedral connectivities, but shows deviations up to about 10 ppm in relative difference for O sites with different tetrahedral connectivities. The poor performance for the latter is mainly due to the approximations of the HF method. Our study thus suggests that the ab initio calculation method is a reliable mean for predicting ²⁹Si and ¹⁷O NMR parameters for silicates. Such an approach should find application not only to well-ordered crystalline phases, but also to disordered materials, by combining with other techniques, such as the molecular dynamics simulation method.     

Characterisation of (17)O-enriched alumina from a new hydrothermal preparation

A novel method for the hydrothermal synthesis of ¹⁷O-enriched -Al₂O₃ is presented. Its advantage compared to commonly used methods is that Al₂O₃ is directly produced from metallic Al and ¹⁷O-enriched H₂O without formation of intermediate Al-hydroxide phases that require subsequent dehydration. This is a much more efficient use of the ¹⁷O label as the Al₂O₃ has similar ¹⁷O enrichment level as the H₂O initially used.     

Nuclear moments for the neutrinoless double beta decay II

The recently developed formalism for the evaluation of nuclear form factors in neutrinoless double beta decay is applied to ⁴⁸Ca, ⁷⁶Ge, ⁸²Se, ¹⁰⁰Mo, ¹²⁸Te and ¹³⁰Te nuclei. Explicit analytical expressions that follows from this theoretical development, in the single-mode model for the decay of ⁴⁸Ca, have been worked out. They are useful both for testing the full numerical calculations, and for analytically checking the consistency with other formalisms. Large configuration space calculations are compared with previous studies, where alternative formulations were used. Yet, besides using the G-matrix as residual interaction, we here use a simple δ-force. Attention is paid to the connected effects of the short range nuclear correlations and the finite nucleon size. Constraints on lepton number violating terms in the weak Hamiltonian (effective neutrino Majorana mass and effective right-handed current coupling strengths) are deduced.     

Magnetic moments of light nuclei

Magnetic moments of the nuclei ¹⁵N, ¹⁵O, ¹⁷O, ¹⁷F and ¹⁹F are investigated. The importance ; of configuration mixing as well as meson-exchange currents is discussed in detail. Meson-exchange currents are treated in the one-boson exchange limit. Short-range N-N correlations are obtained from solutions of the Bethe-Goldstone equation for doubly closed shell nuclei by the use of realistic N-N potentials which ensure a correct treatment of tensor correlations.     

Nuclear Level Density with Non-zero Angular Momentum

The statistical properties of interacting fermions have been studied for various angular momentum with the inclusion of pairing interaction. The dependence of the critical temperature on angular momentum for several nuclei, have been studied. The yrast energy as a function of angular momentum for 28Si and 24 Mg nuclei have been calculated up to 60.0 MeV of excitation energy. The computed limiting angular momenta are compared with the experimental results for ^26Al produced by ^12C＋ 14N reaction. The relevant nuclear level densities for non-zero angular momentum have been computed for ^44Ti and ^136 Ba nuclei. The results are compared with their corresponding values obtained from the approximate formulas.     

A study of the Ti(He, t) and Ni(He, t) reactions to isobaric analogue states

The (³He, t) reaction populating 0⁺ and 2⁺ states in ^{58, 60}Cu and ^{46, 48}V which are isobaric analogue states (IAS) of the 0⁺ ground states and 2⁺ first excited states in ^{58, 60}Ni and ^{46, 48}Ti have been studied at an incident ³He energy of 24.6 MeV. Triton spectra were measured for the targets ^46,48Ti, ^natNi and ⁵⁸Ni and angular distributions for the 0⁺ and 2⁺ IAS of ^{46, 48}Ti and ^{58, 60}Ni determined. The data were obtained using a magnetic spectrometer and position-sensitive detectors. The results have been analysed using DWBA theory. The 0⁺ → 0⁺ transitions to analogue states are described quite well using a microscopic form factor derived from a nucleon-nucleon interaction. However, with a Gaussian form, the m.s. radius of this interaction is only limited to the region 0–9 fm². Comparisons with data at other incident energies indicate that the strength of the effective interaction is strongly energy dependent. The Coulomb energies and (³He, t) angular distributions of the states assigned as the 2⁺ analogues in ⁴⁸V and ^58,60Cu are not described well by the models investigated. The ⁴⁶V 2⁺ IAS angular distribution is reproduced by a microscopic calculation, however. The ratios of the 0⁺ → 2⁺ IAS to the 0⁺ → 0⁺ IAS transitions are used to deduce a quadrupole deformation for the valence neutrons. The difference in the quadrupole deformations of the matter and proton distributions, as determined by other means, is found to be correlated with those of the valence neutrons. Several transitions to non-analogue states are also investigated.     

Elastic and inelastic scattering of neutrons from Fe and Cu : (I). Measurements from 8 to 14 MeV and a spherical optical model analysis

Differential cross sections were measured at 8, 10, 12 and 14 MeV for elastic scattering of neutrons from enriched samples of ⁵⁴Fe, ⁵⁶Fe, ⁶³Cu and ⁶⁵Cu. Inelastic scattering to the first excited state in ^{54, 56}Fe was also observed. For the ^{63, 65}Cu isotopes, the inelastic cross sections for scattering to the combined group of the three (five) states were determined at 8 and 10 MeV (12 and 14 MeV). The elastic scattering data are compared to predictions of earlier global optical models. New spherical optical model representations were obtained. These data were combined with data for nickel, tin and lead to generate a new global parametrization. Comparisons of derived volume integrals for the potentials, total cross sections and potential radii are made to available information.     

积分中值定理在放射性氙样品γ谱效率刻度技术中的应用

在实验室HPGe探测器测量分析氙气样品过程中需要用到相对方法进行分析, 然而由于放射性氙同位素半衰期较短, 制作相应的标准气体比较难, 给谱仪系统刻度带来困难.针对该问题, 提出使用混合面源模拟刻度四种氙同位素气体源的效率, 并提出将积分中值定理应用到面源刻度实验过程, 大大简化了中间流程, 提高了测量的准确性.利用氙分离纯化系统在高氡环境下采集样品, 获得了天然放射性¹³³Xe气体γ谱, 通过计算得到其活度浓度. 积分中值位置处的混合面源刻度结果和气体源刻度结果一致, 说明本文提出的面源刻度技术及积分中值定理的思想在HPGe 探测器效率刻度测量分析中是有效可行的. 关键词： 面源 无源效率刻度软件 效率刻度     

关于93Mo中21/2+晕阱的来源(英文)

本研究通过壳模型计算研究了N=51的同中子素91Zr、93Mo和95Ru中高自旋晕态21/2+的同核异能态现象。计算发现,低角动量的p_1/2轨道上的质子是仅在93Mo中存在21/2+晕阱的主要原因。同时,本工作还研究了N=52的同中子素92Zr、94Mo和96Ru中10₁+-12₁+能级结构的系统性,发现94Mo中的10₁+-12₁+能级间隙相对最小,考虑到与93Mo的17/2₁+-21/2₁+能级相似的组态,这一结果为93Mo中出现21/2+晕阱提供了补充性的论证。Isomerism of the high-spin yrast 21/2+ states of the N=51 isotones 91Zr, 93Mo and 95Ru has been investigated using the shell model calculations. It is found that the low-j πp_1/2 is responsible for the only yrast trap in 93Mo. In addition, the relatively smaller 10₁+-12₁+ level spacing in 94Mo has been found by investigating the systematics of the 10₁+-12₁+ level structures in the N=52 isotones 92Zr, 94Mo and 96Ru. This result provides a supplementary argument to the origin of the 21/2+ yrast trap in 93Mo from the viewpoint of the similarity between the configurations of 10₁+-12₁+ states in 94Mo and those of 17/2₁+-21/2₁+ states in 93Mo.