电气和电子工程用材料科学

TN04 99030026拉伸状态Nbse3在纵向磁场下的负磁阻效应/郑萍,江庆,陈兆甲,金铎(中国科学院低温中心)11低温物理学报.一1998,20(6)一462一467研究了准一维电荷密度波材料Nbse3晶须自然状态(。=0)和受到拉伸的状态(。>0)下在纵向磁场中的磁阻效应.温度T‘5 OK时,无论自然状态还是拉伸状态(。二1.5崎都没有观察到负磁阻.但是,当温度升高到士=70K,作者观察到Nbse。晶须受到拉伸至。=1 .5%时有负磁阻效应;进一步增大。至1.8%负磁阻效应更明显;不拉伸(。=0)则没有磁阻.文中就这个现象进行了讨论.图5表1参9(木)和表面构态信息,揭示了电致发光薄…     

SJ／T 11390—2009《无铅焊料试验方法》概要

范围 本标准规定了无铅焊料的熔化温度、机械拉伸、扩展、润湿、焊点拉伸与剪切、QFP引线焊点45°拉伸、片式元件焊点剪切和焊料动态氧化出渣量的试验方法,适用于锡基无铅焊料. 试验用标准大气条件:除特殊规定外,试验气候条件为温度15℃～35℃.     

V型电致热微驱动器的力学特性分析

运用能量法推导并建立了一种V型悬臂粱电热微致动器的力学模型.利用该力学模型得到了致动器的力学特性,并且与相关的实验结果进行了对比.由理论分析和实验对比发现,用于制造该电热微致动器的多晶硅材料在微米级尺度下的热膨胀系数与温度之间不再遵循宏观状态下的线性函数关系.     

PVDF压电系数d31受温度影响的试验测定

为获得PVDF薄膜压电系数d31在不同温度时的值,采用了准静态拉伸的直接测量技术.简要介绍了准静态拉伸的测量方法及其试验装置,给出了试验结果.通过试验,精确地测定了PVDF在温度范围为-20～+70℃内压电系数d31的值,同时试验也表明,准静态拉伸测量薄膜压电特性的试验方法简单可靠,测量结果合理.     

调质状态下30CrMnSiA钢的激光焊接接头性能与组织

研究了调质状态下激光焊接 30CrMnSiA钢时焊缝的金相组织、显微硬度及热影响区性能变化 ,分析了焊接接头的拉伸机械性能及拉伸试样断口形貌。结果表明 ,在焊接参数匹配和工艺技术措施选择合理的情况下 ,采用激光焊接调质状态下的 30CrMnSiA钢 ,焊接接头的性能和组织优良 ,热影响区硬化、脆化和软化等性能上的变化问题并不突出 ,焊后不需热处理即可保证焊接接头的性能。调质状态下 30CrMnSiA钢激光焊接工艺参数选定的主要出发点应是防止裂纹和保证焊缝表面成形质量。     

玻璃钢锚杆加载过程红外辐射实验研究

应用红外探测技术,对玻璃钢锚杆进行了单向拉伸的红外辐射实验研究,结果表明:玻璃钢锚杆拉伸过程中,其红外辐射温度随着荷载的增加而增加,弹性阶段温升变化微小,塑性阶段温升明显,尤其是临近破裂时,温度升高最快,最大温升值为0.3℃.利用玻璃钢锚杆材料的红外辐射温度特征,可以反演该种材料的锚杆与围岩相互作用过程中的应力、应变以及变形等力学性质.     

双相10钢断裂特征的扫描电镜研究

本文通过在扫描电镜上观察和分析拉伸试样颈缩区中孔洞的分布状态以及拉伸和冲击条件下的断口形貌和裂纹扩展路径,研究了具有不同组织状态的低碳双相钢的断裂特征。结果表明,不同的热处理规范(淬火及回火温度)由于改变钢中铁素体—马氏体两相的体积百分比及强度比,对双相钢颈缩区中孔洞密度、孔洞平均值径及拉伸和冲击条件下的断裂过程均有明显影响。     

真空退火的CdTe/Au掺杂HgCdTe界面状态的影响

对使用CdTe覆盖的HgCdTe材料在不同温度下进行了一系列的退火实验.研究发现,退火可以改善电子束蒸发CdTe的晶体状态,使CdTe和HgCdTe之间的界面状态得到改善.Au掺杂HgCdTe覆盖CdTe后,真空条件下退火,240℃和300℃对Au掺杂的浓度分布改变不大,Au掺杂的浓度几乎不变.但是,温度的不同会对汞空位的浓度产生显著的影响,因此退火温度不同会使载流子浓度明显不同.退火温度从240℃升高至300℃后,霍尔测试得到的载流子浓度从2×10~(16)cm~(-3)左右升高至5.5×1016cm~(-3)左右.     

焊点尺寸对微焊点拉伸断裂强度的影响

采用基于动态力学分析仪(DMA)的精密拉伸试验与ANSYS有限元数值模拟方法研究了“铜引线/Sn-3.0Ag-0.5Cu钎料/铜引线”三明治结构微焊点(直径均为200 μm,高度为75～225 μm)的拉伸断裂行为.结果表明:微焊点直径不变而高度为225,175,125和75 μm时,其拉伸断裂强度分别为79.8,82...     

全息干涉法研究裂纹尖端应力状态的分布

用二次曝光全息干涉法,对有机玻璃材料试件,用小载荷静力加载方式,对单向拉伸单边裂纹有限宽板进行了试验研究,获得了裂纹尖端近区全场应力分布全息图。 单边裂纹有限宽板承受单向拉伸载荷时,近裂纹端的弹性应力场的理论解和光测弹性力学主应力和与等厚干涉条纹级数之间的关系式,当θ=0时,可以推导出关系式n/n_∞=F(2a/r)~(1/2)。因为a、r已知,n、n_∞可由试验测定,从而可以确定F。再由公式K_1=Fσ(πa)~(1/2)即可得到Ⅰ型应力强度因子K_1。     

烧结气氛对烧结NdFeB磁体显微结构的影响

对NdFeB合金的Ar保护烧结和真空烧结进行了对比研究。SEM显微观察发现,与Ar保护烧结的磁体相比,真空烧结磁体中的点状和块状富Nd相相对较小,且存在着明显的线状缺陷。蒸气压理论计算表明,真空烧结时烧结保温过程中Nd和添加元素Dy的饱和蒸气压均大大高于外压,因此Nd和Dy均存在着明显的挥发和烧损,这是造成真空烧结磁体中富Nd相较小以及存在着明显的线状晶界缺陷的主要原因。     

真空微波器件超高真空排气设备测温系统误差的校正

通过分析真空微波器件和排气台经常出现的高温（550℃）漏气的现象,发现现有排气台烘箱测温系统存在问题。从理论上对这一问题进行了分析,并在实验上验证了这一分析。理论和实验表明,随着温度的升高,现有排气台烘箱显示温度与真实温度相差增大。真实温度比最高显示温度高71℃。解决了困扰微波管排气工艺过程中高温漏气的难题。     

High voltage breakdown of titania in vacuo

The electrical breakdown of titania in a vacuum using static electric fields is investigated experimentally, by examination of current and temperature variation at different applied voltages. Thermal instability is found to occur at voltages above a critical value. This leads to sufficiently high temperatures to cause the reduction of the titania into a lower-order semiconducting oxide, which carries the breakdown current. The breakdown of titania and a vacuum gap in series is also investigated. Evidence gathered from temperature and current readings suggests that, at high voltages, part of the voltage originally across the vacuum gap appears across the titania. Evidence to support this theory is obtained from measurements of the mechanical force appearing across the vacuum gap which enable the voltage redistribution to be calculated. The voltage redistribution is due to an excess charge appearing on the surface of the ceramic, due to pre-breakdown currents in the vacuum gap. When the voltage across the titania reaches a large enough value, thermal instability occurs leading to breakdown of the titania.     

High field activation of micropipes in high resistivity silicon carbide

Micropipes in high resistivity (p≥5 kΩcm) SiC are highly activated in parallel electric fields (vertical devices) at room temperature starting at very low fields of 5-10 kV/cm, especially in the doped material. No activation of micropipes is observed in high fields (>100 kV/cm) perpendicular to their orientation (lateral devices). In the last case, the high field limitation is due to surface flashover phenomena taking place at 100-175 kV/cm in vacuum ambient and depending strongly on the material growth technology and the gap length. Non-ohmic behavior was not observed in lateral devices up to high applied fields. The high field characterization method is proposed as a powerful tool for the evaluation of the quality of SiC material for next-generation high voltage/high power devices.     

等离子体辅助镀膜

本文介绍了等离子体辅助镀膜技术以及相应的高真空等离子体源.这种新型等离子体源属于空心冷阴极结构,工作气压在1×10-3pa～10-1pa,它的最大优点在于能够直接电离氧化性气体而不烧毁阴极.采用探针法测定了氩等离子体中辅助离子的能量范围在50～80Ve之间,并在氩气、氧气的等离子体中分别沉积了单层ZnS薄膜和SiO2薄膜.实验结果表明,生成的薄膜具有良好的光学和机械性能.     

Impact of vacuum and nitrogen annealing on HVE SnS photoabsorber films

Researchers worldwide focus on new earth abundant and cheap absorber materials for use in thin film solar cells that allow wider use of photovoltaics in energy production. SnS is one of such promising absorber materials that comprises earth abundant elements (Sn, S). We describe here the effect of annealing of high vacuum evaporated (HVE) SnS thin films in vacuum and nitrogen atmosphere with relatively high pressures of nitrogen. SnS thin films with a thickness of 500 nm were deposited onto the surface of glass by HVE at a substrate temperature of 300 °C. The as-deposited SnS thin films were annealed at 500 °C and 550 °C for 1 h in vacuum as well as in nitrogen with respect to ambient (N₂) pressure that varied in the range of 500–2000 mbar. We analyze crystalline quality, crystal structure, elemental and phase compositions, and electrical properties of SnS films before and after the annealing process and their changes. Our results show that the use of pressurized inert ambient, such as nitrogen, improves the crystalline quality as well as the electrical properties of SnS thin films. The enhanced growth of crystals and modification of microstructural properties of SnS thin films as a function of annealing conditions (type of ambient, annealing temperature and ambient pressure) are discussed in detail.     

A wafer-handling interface under processing ambient conditions fora single-wafer cluster tool

The pretreatment process used in semiconductor manufacturing can include over one-hundred processes, and about 90% of the wafer transfers are done between processors or process chambers that have different ambient conditions from each other; that is, between the atmosphere and a vacuum ambient or between a low and a high vacuum ambient. The throughput and yield from a semiconductor manufacturing line can be greatly improved by reducing the pumping and setting time of each process chamber ambient that is needed when transferring a wafer. We previously proposed a wafer-handling interface that operates under processing ambient conditions (the WHIPAC), with which the processing ambient conditions in the process chamber need not be changed for every wafer exchange and processing ambient fluctuations can be made smaller. We have developed a WHIPAC that allows the wafer in a process chamber under processing ambient conditions to be exchanged with a small mobile buffer chamber located in the transfer chamber at the center of a cluster tool used for single-wafer processing. This paper describes the principle of the WHIPAC for a single-wafer cluster tool and discusses the experimental results obtained from tests of a prototype system     

高功率环行器的温度特性研究

阐述高功率结式环行器的温度特性与偏置磁场的内在联系,给出提高温度特性的方法,据此可以在室温下清楚预知环行器高低温特性,从而减少因温度性能造成的不合格品比率,这一点对宽带工作的环行器尤为重要。     

高温烧结羟基磷灰石靶的细胞相容性

为研究高温烧结羟基磷灰石靶的细胞相容性,把纯度为99%的羟基磷灰石粉末压制成圆盘形靶,在氩气中在800℃高温下烧结成型。用X射线衍射仪和X射线光电子能谱仪对羟基磷灰石靶的结构组成进行检测。用四氮唑盐比色法对羟基磷灰石靶的细胞相容性进行检测。检测结果表明：纯度为99%的羟基磷灰石粉末在压制成型和800℃高温烧结的过程中化学组成没有发生变化,羟基磷灰石靶中的平均粒径为78.2nm、结晶度为89.4%、Ca/P比值为1.592,具有很好的细胞相容性。     

Influence of the surrounding ambient on the reliability of the electrical characterization of thin oxide layers using an atomic force microscope

Physical and electrical properties of thin oxide films have been studied using the atomic force microscope (AFM). Experiments have been done in three different surroundings: in air and in secondary vacuum (∼10⁻⁶ mbar) without and with a heating stage in order to study the influence of the surrounding ambient on the reliability of the electrical characterization of thin oxide films. It is shown that by applying a positive voltage at the AFM tip and in the presence of a water layer at the oxide’s surface in air ambient, the behavior of the oxide film is very different compared to the same experiment conducted in secondary vacuum. It is thought that in air, H⁺ ions are injected through the oxide, forming attached hydrogen defects in it. These electrically active defects form a path in the oxide between the tip and the substrate facilitating the passage of charges through the oxide, which can be described by a Trap Assisted Tunneling (TAT) mechanism. The results show that working in vacuum with a heating stage is an important condition for the reliability of the characterization of oxides since the breakdown phenomenon is largely reduced due to the absence of the water layer. Moreover, the creation of hillocks (protrusions appearing on the surface after the electrical stress) on the oxide’s surface is decreased under vacuum.