Real time electron microscopy observation on morphological changes in gold nano structures deposited on Si (100) surfaces as a function of annealing temperatures has been reported. Two types of interfaces with the substrate silicon were used prior to gold thin film deposition: (i) without native oxide and on ultra-clean reconstructed Si surfaces and (ii) with native oxide covered Si surfaces. For a \approx 2.0 nm thick Au films deposited on reconstructed Si(100) surfaces using molecular beam epitaxy method under ultra high vacuum conditions, aligned four-fold symmetric nanogold silicide structures formed at relatively lower temperatures (compared with the one with native oxide at the interface). For this system, 82% of the nanostructures were found to be nano rectangles like structures with an average length \approx 27 nm and aspect ratio of 1.13 at \approx 700°C. For \approx 5.0 nm thick Au films deposited on Si (100) surface with native oxide at the interface, formation of rectangular structures were observed at higher temperatures (\approx 850° C). At these high temperatures, desorption of the gold silicide followed the symmetry of the substrate. Native oxide at the interface was found to act like a barrier for the inter-diffusion phenomena. Structural characterization was carried out using advanced electron microscopy methods.
Local probing of superconductivity at oxide interfaces with atomic force microscopy
National Institute of Standards and Technology（美国国家标准与技术研究院）；Joint Quantum Institute, Department of Physics, University of Maryland（马里兰大学物理系联合量子研究所）；Department of Advanced Material Science, The University of Tokyo（东京大学先进材料科学系）；Department of Physics and Astronomy, University of Pittsburgh（匹兹堡大学物理与天文学系）；Department of Materials Science and Engineering, University of Wisconsin–Madison（威斯康星大学麦迪逊分校材料科学与工程系）；Department of Chemistry and Biochemistry, University of Maryland（马里兰大学化学与生物化学系）；Institute of Experimental and Applied Physics, University of Regensburg（雷根斯堡大学实验与应用物理研究所）
Structural peculiarities of $\varepsilon$-Fe$_2$O$_3$ / GaN epitaxial layers unveiled by high-resolution transmission electron microscopy and neutron reflectometry
采用脉冲激光沉积法在半导体GAN（0001）衬底上生长了亚稳铁氧化物（$\varepsilon$ -Fe $_2$ O $_3$）外延膜，并对其晶体学特性进行了结构研究。纳米级$\varepsilon$ -Fe $_2$ O $_3$薄膜的柱状结构已被首次使用高分辨电子显微镜（HRTEM）直接空间技术辅以倒易空间方法的高能电子衍射和彩色增强HRTEM图像傅立叶滤波。通过中子反射仪和能量色散X射线光谱法对$\varepsilon$ -Fe $_2$ O $_3$ / GAN界面形成进行了深度分辨密度和化学成分分析，进一步扩展了对界面形成的研究。研究结果揭示了位于$\varepsilon$ -Fe $_2$ O $_3$ / GAN界面的几纳米厚的低密度过渡层的性质和来源。该层的性质的详细知识被认为对于$\varepsilon$ -Fe $_2$ O $_3$ / GAN异质结构的开发是非常重要的，所述异质结构可以潜在地成为具有室温磁电耦合的基于铁氧化物的半导体上铁器件的一部分。
Developing a Chemical and Structural Understanding of the Surface Oxide in a Niobium Superconducting Qubit
铌的超导薄膜已广泛用于transmon量子位架构中。虽然这些架构近年来已经取得了显着的进步，但通过材料工程进一步提高性能将有助于大规模部署。在这里，我们使用从二次离子质谱和电子显微镜检索的信息进行详细的评估，在环境条件下形成的transmon测试量子位器件从铌膜图案化的表面氧化物。我们观察到，这种氧化物表现出不同的化学计量与NbO和NbO $_2$发现更接近铌膜和Nb $_2$ O $_5$发现更接近表面。在结构分析方面，我们发现，Nb $_2$ O $_5$区域是半结晶的性质，并表现出随机取向的晶粒上的顺序为1-2纳米对应于单斜N-Nb $_2$ O $_5$分散在整个非晶基体。使用波动电子显微镜，我们能够映射在Nb $_2$ O $_5$区域的相对结晶度与纳米空间分辨率。通过这种关联方法，我们观察到非晶区更可能含有氧空位，并且铌和氧原子之间的键合更弱。基于这些发现，我们预计氧空位可能作为量子系统中的退相干机制。
