共查询到20条相似文献,搜索用时 78 毫秒
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将金属Ni和石墨粉通过机械混合的方法加入预合成的BaTiO3粉体中,在1230~1260℃下保温20min烧成Ni/石墨/BaTiO3复合正温度系数(PTC)材料。由这种复合材料所制试样具有较低的室温电阻率和较好的PTC效应。通过对实验结果的分析,同时利用XRD、SEM、EDS等手段对复合材料的物相进行分析并对材料的微观形貌进行观察和研究后,提出了该复合材料的显微结构模型和晶界势垒模型,这两种模型从微观层面上解释了加入的Ni和石墨对该复合材料的室温电阻率、PTC效应及耐电压性能的影响,与实验中观察到的现象相符合。 相似文献
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BaTiO3正温度系数(PTC)陶瓷因其具有较高的室温电阻率而使其在低压领域中的应用受到限制,因此,有必要降低其室温电阻率.低阻化的一个途径是将金属与BaTiO3基PTC陶瓷复合来制备复合PTC材料.采用传统陶瓷工艺制备Ni/(Ba,Sr)TiO3复合PTC材料.为避免金属Ni被氧化,复合材料在弱还原气氛下烧成.为排除烧结气氛的影响而讨论金属Ni的影响,(Ba,Sr)TiO3 PTC陶瓷也在同一弱还原气氛下烧成.PbO-B2O3-ZnO-SiO2系玻璃料的加入改善了复合材料的两相分布,优化了复合材料的性能. 相似文献
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Ag基反射镜提高了薄膜型LED芯片的出光效率,但其易受破坏,通常选择抗腐蚀金属作为其保护材料,同时需要研究保护金属与p-GaN的接触性能,避免在p-GaN上同时形成两种欧姆接触引入的电流分流效应。通过传输线的方法研究了Pt,Cr,Ni/Ag与p-GaN的接触行为(在不同的合金条件),讨论了Cr和Pt作为保护材料的可行性。结果发现,N2中500℃合金后,NiAg/p-GaN的比接触电阻率(ρc)达到最低,ρc最低值为1.42×10-3Ω.cm2;同条件下,80 nm Pt/p-GaN的ρc为6.63×10-3Ω.cm2,30 nm Cr/p-GaN的ρc为2.03×10-2Ω.cm2,且其合金前的ρc为5.74×10-2Ω.cm2,比合金后的ρc更高。这说明,Cr是更为理想的Ni/Ag保护材料,若Ni/Ag合金后再蒸Cr,效果更佳。最后,通过芯片老化实验,验证了Cr是一种较为理想的、可靠的反射镜保护材料,采用其制备的薄膜型功率芯片具有很高的可靠性。 相似文献
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利用金属有机化合物化学气相淀积(MOCVD)在SiC衬底上外延生长了N-polar GaN材料,采用传输线模型(TLM)分析了Ti/Al/Ni/Au金属体系在N-polar GaN上的欧姆接触特性.结果表明,Ti/Al/Ni/Au (20/60/10/50 nm)在N-polar GaN上可形成比接触电阻率为2.2×10-3Ω·cm2的非合金欧姆接触,当退火温度升至200℃,比接触电阻率降为1.44×10-3 Ω·cm2,随着退火温度的进一步上升,Ga原子外逸导致欧姆接触退化为肖特基接触. 相似文献
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采用Ti/Al/Ni/Au多层金属体系在Al0.27Ga0.73N/GaN异质结构上制备了欧姆接触.分别采用线性传输线方法(LTLM)和圆形传输线方法(CTLM)对其电阻率进行了测试.当Ti(10nm)/Al(100nm)/Ni(40nm)/Au(100nm)金属体系在650℃高纯N2气氛中退火30s时,测量得到的最小比接触电阻率为1.46×10-5Ω·cm2.并制备了Al0.27Ga0.73N/GaN光导型紫外探测器,通过测试发现探测器的暗电流.电压曲线呈线性分布.实验结果表明在Al0.27 Ga0.73N/GaN异质结构上获得了好的欧姆接触,能够满足制备高性能AlGaN/GaN紫外探测器的要求. 相似文献
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为了得到低烧结温度、较低室温电阻率的BaTiO3基半导体陶瓷,提出在BaO-B2O3-SiO2-MnO烧结助剂中加入LiF的方法,研究了BaO-B2O3-SiO2-MnO-LiF(BBSML)烧结助剂对Y3+与Nb5+双掺杂BaTiO3基热敏陶瓷的微观结构和正温度系数(PTC)特性的影响。微观结构分析表明:玻璃助剂中LiF的含量能改变晶界相组成,影响样品的烧结特性和室温电阻率。实验结果表明,x(LiF)=5%的BBSML烧结助剂的样品,在1 050℃保温1 h下烧结后,其室温电阻率为151Ω.cm,升阻比为5.6×103。 相似文献
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为减少球形Ni/Al填充量并提高Ni/Al填充导电硅橡胶屏蔽效能,选取Ni/C纤维加入到此种导电橡胶中,并从导电性、屏蔽性能方面对其进行评价。实验发现Ni/C纤维的掺杂可以提高导电橡胶的导电性及屏蔽性能。当总颗粒填充量为130 phr时,掺杂纤维使导电橡胶的体积电阻率从1010Ω·cm降至1.4Ω·cm;当总颗粒填充量为240 phr时,在1.0~2.5 GHz的频段内,其屏蔽效能在90 d B以上,而未经过掺杂的仅能超过60 d B。利用面心立方堆垛结构模型计算颗粒间最小距离,结果发现导电橡胶的渗流阈值与颗粒最小间距有较为明显的相关性。 相似文献
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This study investigates the electromigration effect upon the Zn/Ni and Bi/Ni interfacial reactions by using reaction couple
techniques. Three phases, β1-NiZn, γ-Ni5Zn21, and δ-NiZn8 formed in the Zn/Ni couples reacted at 150°C and 200°C for 4 h to 360 h, and the reaction layers grow thicker with longer
reaction time. Passage of a 300 A/cm2 current through the Zn/Ni couples has no significant effect upon the interfacial reaction. There is no noticeable difference
in the phase formation and layer thickness of the two kinds of Zn/Ni couples with and without the passage of electric currents.
Only NiBi3 phase was found in the Bi/Ni couples reacted at 150, 170, 185 and 200°C. Passage of a 300 A/cm2 electric current through the Bi/Ni couples did not change the phase formation, and growth rates of the NiBi3 phase in the couples reacted at 185°C and 200°C were not affected by passage of electric currents either. However, growth
rate of the NiBi3 phase was enhanced in the Bi/Ni couples reacted at 150°C and 170°C with the passage of a 300 A/cm2 electric current. A mathematical model was proposed to describe the electromigration effect upon the growth of the intermetallic
compounds. Physical parameters in the models were determined by optimization based on experimental measurements, and the results
indicate that the values of the apparent effective charge of Bi and Ni decreased sharply with increasing temperatures. 相似文献
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Joondong Kim Eung-Sug Lee Youngjin Kang Wayne A. Anderson 《Microelectronic Engineering》2008,85(8):1709-1712
The Ni silicide nanowires were grown by physical vapor deposition. The morphological changes of silicide formation were observed on a gradient Ni film thickness, which visualized the critical thickness is 60-80 nm to grow nanowires. The field emission measurement provided uniform characteristics and high field enhancement factors were obtained to be 3180 and 3002 from the Ni silicide nanowires grown on a Si substrate and a tungsten plate, respectively. By using a conductive tungsten plate, the emission current was enhanced to be 172.5 μA/cm2 comparing to 76.5 μA/cm2 from a Si substrate at 5 V/μm. 相似文献
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The contact resistance of alloyed NiAuGeNi contacts has been measured on n-GaAs. The quality of the contacts was strongly influenced by the pre-evaporation cleaning of the semiconductor surface. Compared to chemical etching, sputter cleaning considerably reduced the contact resistance and improved reproducibility. Optimization of the alloying cycle led to contact resistances lower than the state of the art. 相似文献
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Atmospheric corrosion has vast consequences on the reliability of electronic connectors. This study determined the corrosion resistance of Ni/Ni–P plating metallurgy as a function of plating current density and plating thickness. Discrepancy was observed in the neutral salt spray (NSS) and mixed flowing gas (MFG) tests. Thicker Ni–P deposits displayed superior corrosion resistance in MFG tests while thinner Ni–P deposits performed better in NSS tests. This disparity was attributed to the intrinsic corrosion susceptibility of Ni–P against chlorine or sulfur assisted corrosion. Corrosion products were analysed for better understanding of the corrosion mechanism. NSS test produced green corrosion residues consisting of CuCl (nantokite) and CuCl2(OH)3 (clinoatacamite) and brown residues consisting of Cu2O (cuprite). MFG test produced sulfides of copper (major) and nickel (minor). 相似文献
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Specimens with the Sn/Cu/Sn/Ni/Sn/Cu/Sn structure reacted at 200°C are prepared and examined. The Cu6Sn5 and Cu3Sn phases are formed at the Sn/Cu interface, and the Cu6Sn5 and Ni3Sn4 phases at the Sn/Ni interface. The reaction path in the original Cu/Sn/Ni part of the specimen is Cu/Cu3Sn/Cu6Sn5/Sn/Cu6Sn5/Ni3Sn4/Ni. The peculiar phenomenon of the Cu6Sn5 phase forming at both sides of the Sn phase is illustrated using the Sn-Cu-Ni phase diagram with a very wide compositional-homogeneity
range of the Cu6Sn5 phase. Interfacial reactions at 240°C between pure Sn and (Cu,Ni) alloys of various compositions are determined. The Cu6Sn5 phase is formed when the NI content is less than 30 wt.%, and the Ni3Sn4 phase is formed when the Ni content is higher than 40 wt.%. When the Ni content is between 35 wt.% and 40 wt.%, both Cu6Sn5 and Ni3Sn4 phases are formed. It is also noticed that the formation of the Cu3Sn phase at the Sn/(Cu,Ni) interface is suppressed with more than 1wt.%Ni addition in the substrate. 相似文献
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研究了AlGaN半导体p电极的Ni/Au/Ni/Au接触结构的性能和组织结构。退火
前,p电极接触具有明显的整流特性。经空气中550℃/3 min一
次退火和N2气氛中750℃/30 s二
次退火后,电极呈现出了良好的欧姆接触。采用扫描电镜(Scanning Electron Microscope, SEM)、透射
电镜(Transmission Electron Microscope, TEM)、能量分散谱仪(Energy Dispersive Spectrometer, EDS)和X射
线光电子能谱(X-ray Photoelectron Spectroscopy, XPS)观察了电极退火后金--半界面微结构的演化过程。结果表明,完全退火后的p电极
界面及金属层出现了明显的互扩散和界面反应现象;金--半界面上形成了存在良好共格/半共格关系的外延结
构。初始沉积的金属电极分层现象消失,形成了单一的电极结构。Ni向外扩散并与O发生反应,Au扩散至p-GaN
表面。在金-半接触界面上,Ga扩散至金属电极,造成界面附近的金属层中富集Au和Ga元素;Au和Ni明显扩散
至半导体表层,在金-半界面附近形成了Au、Ga和Ni富集现象。这些现象应该对于降低势垒高度和形成欧姆接触具有重要作
用。 相似文献
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Thickness scaling issues of Ni silicide 总被引:1,自引:0,他引:1
O. Chamirian J. A. Kittl A. Lauwers O. Richard M. van Dal K. Maex 《Microelectronic Engineering》2003,70(2-4):201-208
Ni silicidation processes without a capping layer and with a TiN capping layer are studied from the point of view of process window, morphology of the resulting silicide, and mechanisms of degradation at higher temperatures. The thermal stability of NiSi films on As- and on B-doped (100) Si substrates was investigated for Ni film thicknesses ranging from 5 to 30 nm. While agglomeration was the mechanism of degradation for the thin films, both morphological changes and transformation to NiSi2 were possible for thicker films depending on anneal temperature and time. Activation energy of 2.5 eV for NiSi on n+ (100) Si and p+ (100) Si was determined for the process of morphological degradation. The measured temperature and time dependences for the thermal degradation of NiSi films suggest that the activation energy for transformation to NiSi2 is higher than for morphological degradation. 相似文献