Carrier transport across grain boundaries in polycrystalline silicon thin film transistors

We established a model for investigating polycrystalline silicon (poly-Si) thin film transistors (TFTs). The effect of grain boundaries (GBs) on the transfer characteristics of TFT was analyzed by considering the number and the width of grain boundaries in the channel region, and the dominant transport mechanism of carrier across grain boundaries was subsequently determined. It is shown that the thermionic emission (TE) is dominant in the subthreshold operating region of TFT regardless of the number and the width of grain boundary. To a poly-Si TFT model with a 1 nm-width grain boundary, in the linear region, thermionic emission is similar to that of tunneling (TU), however, with increasing grain boundary width and number, tunneling becomes dominant.     

Dielectric properties of Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> ceramics by impedance spectroscopic method

Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi₄Ti₃O₁₂ is a type of ferroelectric ceramics, which is supposed to replace leadcontaining ceramics for its outstanding dielectric properties in the near future. Ferroelectric ceramics of Bi₄Ti₃O₁₂ made by conventional mixed oxide route have been studied by impedance spectroscopy in a wide range of temperature. X-ray diffraction patterns show that Bi₄Ti₃O₁₂ ceramics are a single-phase of ferroelectric Bi-layered perovskite structure whether it is calcined at 800 °C or after sintering production. This study focused on the effect of the grain size on the electric properties of BIT ceramics. The BIT ceramics with different grain sizes were prepared at different sintering temperatures. Grain becomes coarser with the sintering temperature increasing by 50 °C, relative permittivity and dielectric loss also change a lot. When sintered at 1 100 °C, r values peak can reach 205.40 at a frequency of 100 kHz, the minimum dielectric losses of four different frequencies make no difference, all close to 0.027. The values of E _a range from 0.52 to 0.68 eV. The dielectric properties of the sample sintered at 1 100 °C are relatively better than those of the other samples by analyzing the relationship of the grain, the internal stresses, the homogeneity and the dielectric properties. SEM can better explain the results of the dielectric spectrum at different sintering temperatures. The results show that Bi₄Ti₃O₁₂ ceramics are a kind of dielectrics. Thus, Bi₄Ti₃O₁₂ can be used in high-temperature capacitors and microwave ceramics.     

基于Logistic模型分析理工科大学生的就业影响因素

通过问卷调查,用多元统计分析中的二项式Logistic回归模型,对重庆市4所理工科院校毕业生的就业影响因素进行实证分析,结果表明:性别特征、学习成绩、英语水平、获奖等级、担任学生干部、社会实践经历、理想薪酬、意向就业区域、期望单位性质对就业的影响较大.从合理调整学科和专业设置、加强就业创业指导、转变就业观念、构建多学科交叉培养模式、提高毕业生素质等方面提出了相应对策.     

催化裂化油浆系统结垢原因及解决措施

本文讨论了催化裂化(FCC)油浆系统的结垢原因及减少其结垢的措施。介绍了近年来国内外催化裂化油浆的发展状况和应用效果。最后针对我国的实际情况提出了一些设想和建议。     

化学促进剂在酶的直接电化学中的应用

对近几年来国内外在酶的直接电化学反应中所使用的促进剂进行了归纳，对实现酶与电极之间直接电化学的方法和机理进行讨论，并对其未来的发展进行了展望。     

助磨剂在我厂的试验及应用

我厂经质量认证后，水泥3d强度要求在26．0MPa以上，对R3抗压强度的提高，无疑对我厂是一个新的考验，因为我厂1～4号窑熟料早期强度偏低。为确保水泥强度，只得增加比表面积，改善水泥颗粒组成和力求颗粒形状球形化；或降低混合材掺入量，即以牺牲水泥磨机台时产量为代价，从而提高了水泥的制造成本。这种情况下，工厂决定在5～6号水泥磨上试用助磨剂。助磨剂为美国格雷斯公司开发的TDA730型水泥添加剂。工厂成立了试验领导小组，由技术处、化验室、制成车间共同完成。     

生物质废弃物催化气化制取富氢燃料气

利用生物质氢可以实现 CO2 归零的排放 ,从根本上解决化石能源消耗带来的温室效应问题 ,已引起了世界各国研究者的普遍兴趣 .介绍了生物质催化气化制取富氢燃料气的研究概况 ,给出了生物质催化气化制氢的典型流程 ,讨论了在气化过程中发生的主要化学反应以及影响燃料气组成和焦油含量的一些主要影响因素 ,如气化介质的不同及催化剂的应用等     

天然气水合物资源开发现状及前景

天然气水合物被认为是21世纪的主要清洁能源,也是当今世界科学研究的前沿之一。我国开展天然气水合物研究,对我国宏观能源战略决策、开拓新学科领域和社会可持续发展均有重要理论意义和广阔的应用前景。论述了天然气水合物资源及未来,提出了我国应采取的措施及策略。     

调速皮带秤的变频改造

我厂的几套配料系统均使用TDG调速定量电子皮带秤。原来采用TDG专用控制仪表，1994年底至1995上半年陆续更换成深圳某公司的“生料／熟料质量(化学成分)微机配料控制系统”。由于秤体采用电磁调速电动机(滑差电动机)调速，电磁离合器的故障率相当高，从而对计量准确性和配比造成较大的影     

电子提花机控制系统中无线网络技术的研究及应用

为提高国产电子提花机的网路控制能力,在现有电子提花机控制系统的基础上,结合提花织物先进制造的要求及嵌入式无线网络技术,设计了一种基于无线网络通讯技术的电子提花机控制系统.文章描述了WiFi无线通讯技术在电子提花机控制中的实现,给出了PIMCIA接口的无线网卡的应用系统的软硬件设计.试验表明,该系统性能稳定,能够实现网络控制功能.