A Study on Oxidization Processes of YBaCuO Superconducting Thin Films in Atomic Force Microscope Anodization Lithography

概要

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It is essential to elucidate processing mechanism in the fabrication of nano-electronic devices in order to improve their characteristics. In this study, we systematically investigated various experimental parameters in oxidizing a thin film of YBaCuO superconductor, one of the processing steps in producing a superconducting flux flow transistor (SFFT). An area between a gate and a drain in SFFT was selectively modified by controlling the parameters such as an applied bias voltage between a conducting atomic force microscope (AFM) tip and the films, the numbers of the lithographic process on the same area, and the contact resistance between the sample holder and a sample. The height of the lithographed surface was increased with higher applied bias voltage, more numbers of the lithographic process, but was decreased by increasing the contact resistance. The analysis of the data confirmed that the height enhancement results from growth of oxide via an electrochemical reaction. Also analysis of its Raman spectra revealed that the electrical property of the oxidized area became an insulator. The peak 632 cm-1 related with the Cu–O stretching mode in the YBCO structure is disappeared or broad in a sample lithographed above 10 V, which means that the Cu–O chain is affected in superconducting structure by the AFM lithographic process.
2006-03-30