FeCo基纳米晶合金高温交换耦合作用机理

研究了500和600℃真空退火后的纳米晶Fe_38.4Co₄₀Si₉B₉Nb_2.6Cu合金初始磁导率随温度的变化规律,发现较高温度(600℃)退火的FeCo基纳米晶合金,在非晶相居里温度以上较宽温度范围内磁导率没有明显的衰减,这是在双相纳米晶合金中观察到的一种新现象,其磁特性不同于Fe基纳米晶合金.为了探明这种现象的起源,估算了与剩余非晶相同成分的非晶合金的居里温度及纳米晶粒间发生交换耦合作用的参数 关键词： 交换耦合作用 非晶相居里温度 交换耦合穿透深度     

多脉冲励磁下铁氧体及非晶磁环的磁特性

感应脉冲加速器的磁芯通常为铁氧体或非晶材料,而感应腔磁芯在工作脉冲下的磁性能是决定感应加速脉冲波形好坏的重要因素。搭建了低压多脉冲实验平台对铁氧体和非晶小磁环分别进行MHz重复频率的多脉冲励磁,对励磁线圈上的电压电流波形进行监测,绘制了多脉冲励磁下磁环的磁化曲线,并结合含磁芯线圈动态电感量的递推公式计算出磁环在多脉冲励磁过程中磁导率的变化曲线;在高压三脉冲实验平台上对铁氧体磁芯和非晶磁芯实验感应腔进行了高压三脉冲实验,得到的磁芯多脉冲磁化规律与低压实验的结果一致。最后对两种磁环在多脉冲励磁下的磁性能差异进行了对比分析。     

Laser Damage Mechanisms of Amorphous Ta2O5 Films at 1064, 532 and 355nm in One-on-One Regime

Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy （AFM） and x-ray photoelectron spectroscopy （XPS）. The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold （LIDT） is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation （I（λ）=aλm）, which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.     

大尺寸AMOLED显示的技术挑战

综述了目前大尺寸AMOLED显示的技术挑战,尤其是背板技术。然后论述了如何采用氧化物TFT新技术与LTPS和a-Si TFT的优势相结合制造大尺寸背板的最佳方案。通过对比传统准分子激光退火（ELA）LTPS和非晶铟-镓-氧化锌（a-IGZO）TFT的器件特性,特别揭示了氧化物TFT的挑战性技术。最后,展示了由a-IGZO TFT背板制造的12.1in WXGAAMOLED显示器原型机。     

Mechanical behavior of Cu-Zr bulk metallic glasses （BMGs）： A molecular dynamics approach

In the present work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviors of CuZr Bulk metallic glasses (BMGs). The substrate indenter system is modeled using hybrid interatomic potentials including both many-body Finnis Sinclair (FS) and two-body Morse potentials. A spherical rigid indenter (diameter = 60(1 = 10-10 m)) is employed to simulate the indentation process. Three samples of BMGs including Cu25Zr75 , Cu50Zr50 , and Cu75Zr25 are designed and the metallic glasses are formed by rapid cooling from the melt state at about 2000 K. The radial distribution functions are analyzed to reveal the dynamical evolution of the structure of the atoms with different compositions and different cooling rates. The mechanical behavior can be well understood in terms of load-depth curves and Hardness-depth curves during the nanoindentation process. Our results indicate a positive linear relationship between the hardness and the Cu concentration of the BMG sample. To reveal the importance of cooling rate provided during the processing of BMGs, we investigate the indentation behaviors of Cu50Zr50 at three different quenching rates. Nanoindentation results and radial distribution function (RDF) curves at room temperature indicate that a sample can be made harder and more stable by slowing down the quenching rate.     

Composition-Controlled Low Field Magnetostriction of TbFe Amorphous Films

Amorphous TbFe films are fabricated by dc magnetron sputtering, and their magnetostrictions at low field are examined over a wide range of terbium content （from 32at.% to 70at.%）. It is found that the terbium content plays an important role in the magnetic and magnetostrictive properties of TbFe films. TbFe film soft magnetic properties and low field magnetostriction can be efficiently improved by controlling the terbium at an optimum content. The magnetostriction at lower magnetic field is increased with the increase of terbium content up to 48.2at.%. After reaching the maximum value, further increase of terbium content would result in a great decrease of the low field magnetostriction. By contrast, at higher magnetic field, the magnetostriction is decreased monotonically with the increase of the terbium content.     

退火对含氮氟非晶碳膜结构及光学带隙的影响

采用射频等离子体增强化学气相沉积法,在不同条件下制备了含氮氟非晶碳膜,着重考察了退火温度对膜结构和光学带隙的影响. 研究发现：在350℃时,膜仍很稳定,当退火温度达到400℃时,其内各化学键的相对含量发生很大的改变. 膜的光学带隙随着退火温度的升高而增大,红外和拉曼光谱分析显示其原因是：退火使得膜内F的相对浓度降低,sp²相对含量升高,导致σ-σ^*带边态密度降低. 关键词： 含氮氟非晶碳膜 退火 光学带隙     

磁环中非晶丝的阻抗效应分析

依据Landau-Lifshitz阻尼项和Gilbert阻尼项的磁矩转动方程,提出统一形式的磁化率张量表达式.基于等效磁导率将非晶丝中各向异性的电磁场求解问题转化为等效的各向同性问题,进而分析了套在绝缘磁环或导电磁环中非晶丝的阻抗.采用基于有限元的数值方法仿真磁环中非晶丝的阻抗,仿真结果验证了理论分析结论.理论分析和仿真实验均表明,外磁体的附加阻抗将严重降低阻抗变化率,破坏巨磁阻抗特性.为此,提出采用回路形式降低附加阻抗的方法,并基于仿真实验验证了该方法的有效性. 关键词： 巨磁阻抗效应 非晶材料 Maxwell方程 有限元     

SiNX覆盖层厚度对非晶In-Ga-Zn-O薄膜退火晶化的影响研究

采用射频磁控溅射在二氧化硅衬底上沉积一层厚度200 nm的非晶In-Ga-Zn-O(IGZO)薄膜,并在IGZO膜层上沉积厚度分别为20 nm、50 nm、60 nm、70 nm、90 nm的SiNX薄膜覆盖层,于350℃条件下N2气氛中退火1 h.采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、能量色散谱仪(EDS)对IGZO薄膜的微观结构及成分进行研究.研究结果表明,退火后无覆盖层的IGZO膜层仍为非晶状态,70 nm以上SiNX覆盖层下的IGZO薄膜不发生晶化.与此不同,20～60 nm的SiNX覆盖层下IGZO膜层与SiNX覆盖层的界面处存在纳米凸起柱,使IGZO薄膜与SiNX覆盖层的接触界面脱离,此厚度的SiNX覆盖层具有诱导非晶IGZO薄膜晶化的作用,IGZO膜层内部的晶粒直径约10 nm.成分分析结果表明,结晶处In原子含量增加,IGZO薄膜中In原子的局域团聚是IGZO薄膜发生晶化的原因.     

一种基于表面势的非晶态InGaZnO薄膜晶体管核心紧凑模型

考虑非晶态铟镓氧化锌薄膜晶体管(Amorphous InGaZnO thin film transistors,a-InGaZnO TFTs)指数分布的带尾态和深能态,基于表面势的显式解,建立了a-InGaZnO TFTs的核心紧凑模型。解析地求解泊松方程,得到表面势的显式解,与数值迭代算法的计算结果进行比较,其绝对误差小于10-5 V,且提高了计算效率;利用高斯定理与薄层电荷模型,推导漏源电流的解析解;最后对漏电流实验数据进行拟合,提出的模型与实验数据符合得较好,能准确预测a-InGaZnO TFTs的漏电流特性。提出的紧凑模型适用于电路仿真应用。