共查询到18条相似文献,搜索用时 93 毫秒
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本文报道了在10~(-5)—10~(-6)托的高真空下用电子束蒸发制作高质量的Nb超导薄膜的实验结果,Nb膜的临界温度T_c可以达到9.2K,接近大块纯Nb的T_c值(~9.3K)。研究了薄膜厚度、蒸发速率、衬底温度和真空度等淀积条件对Nb膜T_c的影响。用X射线衍射、电子显微和表面分析等方法分析了Nb膜的成分和结构。 用热氧化、直流辉光放电氧化和射频氧化等方法制成了Nb-NbO_x-Pb隧道结,通过表面分析研究了氧化位垒层的成分。对Nb隧道结的稳定性作了初步考察,40个串联结经过61次室温-4.2K之间的热循环和在室温下保存200天以上,结的I-V特性没有显著变化。 相似文献
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本文用选择铌膜刻蚀或选择铌膜阳极氧化过程研究了全铌隧道结Nb/AlOxAl/Nb的制备.借助于SEM,利用曝光后烘烤处理研究了高质量光刻胶图形的制备工艺,并分析了其对铌结特性的影响.结面积为7μm2的铌结具有典型的IV曲线,在4.2K时,他们的特性参数Vm~20mV,能隙电压Vg~2.7mV,临界电流密度Jc~3000A/cm2,比电阻ρn~1μΩcm2.这些铌结能够被直接应用于dcSQUID. 相似文献
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Jiro Yugami 《Superlattices and Microstructures》2000,27(5-6)
For future ULSIs, the oxide reliability problem is a key issue to realize low-power, high-speed devices whilst retaining its reliability. In the MOSFET structure, a gate oxide consists of the substrate/oxide interface, oxide and oxide/gate interface. Therefore, to improve oxide reliability, it is important to control these three component structures individually. In this report, I will describe experiments to control structures of the above two interfaces using: (1) a combination of a closed wet cleaning system and a load-lock oxidation system and (2) an ultra-thin film deposition CVD technique. By controlling these structures, the oxide reliability was improved. Moreover, the interface structure should be carefully controlled in high- k gate dielectrics in future devices. 相似文献
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The growth and properties of gadolinium oxide (Gd2O3) films prepared by anodic oxidation were investigated. Uniform Gd2O3 thin film with good oxide quality was obtained. The X-ray diffraction (XRD) pattern of the Gd2O3 films showed that they had a poly-crystalline structure. The dielectric constants of Gd2O3 films oxidized at 30 and 60 V are 9.4 and 12.2, respectively. The equivalent oxide thickness (EOT) of the Gd2O3 stacked oxide is in the range of 5.8-9.4 nm. The MOS capacitor with Gd2O3 exhibits interesting electrical properties. Longer oxidation time reduced the leakage current density for 30 V anodic oxidation but increased the leakage current density for 60 V anodic oxidation. This work reveals that Gd2O3 could also be an alternative dielectric for Si substrate and therefore, might pave the way to fabricate CMOS devices in the future. 相似文献
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碳/碳化硅(C/SiC)复合材料是应用于临近空间高超声速飞行器热防护的一种新型防热材料.国内外通过性能测试较多地研究了材料不同制备工艺对抗烧蚀性的影响,提出的抗烧蚀分析理论模型均基于液态氧化膜.而近期开展的C/SiC复合材料管式炉加热实验和试样微观形貌电镜表征显示:常压下,当温度低于1 696 K时,C/SiC复合材料氧化后表面形成了多孔的固态氧化膜.采用压汞法测试了氧化物孔隙.基于孔隙中的气体扩散行为,结合氧化反应动力学关系,建立了一种新的C/SiC复合材料惰性氧化模型.模型预测值与实验结果吻合良好,表明该惰性氧化模型对氧化膜厚度和质量损失具有较好的预测能力. 相似文献
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为了从电子层面揭示Nb合金高温氧化的物理本质,采用递归法计算了Nb合金的电子态密度、原子镶嵌能、亲和能等电子结构参数,探索Nb合金高温氧化机理.研究表明:氧在Nb中具备较高的扩散速率和溶解度,且氧与Nb较易发生反应,生成氧化物,这使Nb的抗高温氧化性较差.原子镶嵌能的计算结果表明,合金元素Ti,Si,Cr在基体中稳定性较低,易向Nb合金表面扩散,形成富Ti,Si,Cr的表层.合金表层中氧与Nb,Ti,Si,Cr间具有较大亲和性,可以生成相应的氧化物,形成对合金具有保护作用的氧化膜.
关键词:
递归法
高温氧化
Nb合金 相似文献
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本文基于第一性原理方法,研究水对N复合氧化膜Cr2O3的作用机制。结果表明N的复合影响H2O在表面的吸附位点及吸附高度,N的溶入与Cr形成稳定作用,减缓H2O对表面Cr-O间的破坏作用,改善氧化膜表层结构,提高表面电化学稳定性。因此,N的复合可增强氧化膜对H2O的作用,同时改善氧化膜的结构稳定性,从而提高不锈钢的抗氧化性。 相似文献
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从电子层面系统研究Fe-Cr-Al合金氧化膜的形成机理,杂质硫对氧化膜黏附性的影响,稀土元素在改善氧化膜黏附性方面的作用,揭示合金氧化的物理本质.研究表明氧使Al在合金表层的环境敏感镶嵌能最低,促使Al原子从合金内部向合金表面扩散,最终在合金表面偏聚.由于氧与Al间的亲和力较大,氧原子易与Al结合生成Al2O3保护膜.杂质S在基体/氧化膜界面的环境敏感镶嵌能较低,可通过扩散偏聚在基体/氧化膜界面,削弱氧化膜与合金基体的结合力.当合金中加入Y后,Y易与S结合形成稳定的硫化物,阻碍S向基体/氧化膜界面的偏聚,显著提高氧化膜的黏附性,提高合金抗高温氧化能力. 相似文献
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R. Würz M. Rusu Th. Schedel-Niedrig M.Ch. Lux-Steiner H. Bluhm M. Hvecker E. Kleimenov A. Knop-Gericke R. Schlgl 《Surface science》2005,580(1-3):80-94
The thermal and native oxidation of CuGaSe2 thin films was studied by in situ X-ray photoelectron spectroscopy (XPS). The special design of the XPS chamber allowed to measure XP-spectra under oxidizing gas atmospheres at pressures of up to 5 mbar (in situ) or in ultra high vacuum (UHV). During thermal oxidation, the formation of predominantly Ga2O3 and some amount of SeO2 were observed, but no copper oxides could be detected in the near surface region of the thin films. The same oxides were found after native oxidation in air under ambient conditions. Only after long term native oxidation for longer than 4 months Cu(OH)2 was detected. An additional sodium oxide compound formed at the thin film surface, NaxO and Na2CO3 after thermal and native oxidation, respectively. The amount of these sodium oxide compounds depends on the Na content on the as prepared surface. The formation of SeO2 under humid conditions at 100 °C was found to depend on the surface composition of the thin film. 相似文献