Low energy electron beam processing of YBCO thin films

• Published in: Applied surface science 2017-02, Vol.395, p.42-49
• Main Authors: Chromik, Š., Camerlingo, C., Sojková, M., Štrbík, V., Talacko, M., Malka, I., Bar, I., Bareli, G., Jung, G.
• Format: Article
• Language: English
• Subjects: Electron radiation defects; High-Tc films; Raman spectra; Vortex pinning
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.07.086

•Improvement of superconducting properties of irradiated bridges under certain conditions.•30keV irradiation influence CuO2 planes as well as oxygen chains.•Direct confirmation of changes in oxygen chains using micro-Raman spectroscopy.•Possibility of electron writing. Effects of low energy 30keV electron irradiation of superconducting YBa2Cu3O7−δ thin films have been investigated by means of transport and micro-Raman spectroscopy measurements. The critical temperature and the critical current of 200nm thick films initially increase with increasing fluency of the electron irradiation, reach the maximum at fluency 3−4×1020 electrons/cm2, and then decrease with further fluency increase. In much thinner films (75nm), the critical temperature increases while the critical current decreases after low energy electron irradiation with fluencies below 1020 electrons/cm2. The Raman investigations suggest that critical temperature increase in irradiated films is due to healing of broken CuO chains that results in increased carrier’s concentration in superconducting CuO2 planes. Changes in the critical current are controlled by changes in the density of oxygen vacancies acting as effective pinning centers for flux vortices. The effects of low energy electron irradiation of YBCO turned out to result from a subtle balance of many processes involving oxygen removal, both by thermal activation and kick-off processes, and ordering of chains environment by incident electrons.