X‐ray photoelectron spectroscopy study for Nb Josephson junctions with overlayer structure
X‐ray photoelectron spectroscopy study for Nb Josephson junctions with overlayer structure
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DOI：
10.1063/1.107767
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发表时间：
1992-08
影响因子：
4
通讯作者：
M. Shigeno;S. Morohashi
中科院分区：
文献类型：
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作者：
M. Shigeno;S. Morohashi
我们使用 X 射线光电子能谱研究了以 Al、Zr、Ta、Hf、V 和 Ti 作为薄覆盖层（除 Al 之外的所有过渡元素）的金属/Nb 结构。足以保护Nb免于形成Nb自然氧化物的金属厚度为2.0nm。在具有 Al、Zr、Ta 和 Hf 覆盖层的结构中，光电子光谱中的氧化物峰（由金属表面上生长的原生氧化物产生）随着金属覆盖层厚度的增加而向更高的结合能移动。这些变化归因于金属覆盖和绝缘氧化层。使用 XPS 同时无损地研究了天然氧化物的氧化物绝缘性能和 Nb 表面的金属覆盖度。这些是制造具有优异电流电压特性的铌结的重要因素。
We studied metal/Nb structures with Al, Zr, Ta, Hf, V, and Ti as thin overlayers (all transition elements except Al) using x‐ray photoelectron spectroscopy. The metal thickness sufficient to protect Nb from the formation of Nb native oxide was 2.0 nm. In structures with Al, Zr, Ta, and Hf overlayers, the oxide peaks in the photoelectron spectra, which resulted from native oxide grown on the metal surface, shifted toward higher binding energies with increasing metal overlayer thickness. These shifts were attributed to the metal coverage and the insulating oxide layers. The oxide insulating properties of the native oxides and the metal coverage of the Nb surface were studied at the same time, nondestructively, using XPS. These are essential factors for fabricating Nb junctions with excellent current‐voltage characteristics.