Ion and electron beam irradiation effects for high-Tc superconductors

The report addresses a study which uses thin Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O films to investigate the ion and electron beam irradiation effects, which are expected to provide a means of developing electronic devices. The resistivity increases and the X-ray diffraction intensity decreases as the dose of ion implantation increases. The samples become nearly amorphous when the dose reaches a certain level. Y-Ba-Cu-O samples ion-implanted to a dose of 1x1016 and 1x1017 ions/cm2 are then annealed in an oxygen atmosphere. Results show that the crystallinity is recovered in the former sample while two phases coexist in the latter after annealing at 940degC for 4 hours. The crystallinity in the latter may be further increased under improved conditions. Another effort is made to control the Tc by local ion implantation using focused ion beam. Results suggest that patterning on a superconductor can be easily achieved by using focused ion beam. A study is also made on the effect of electron beam irradiation. It is shown that the characteristics of high-Tc superconductor films can be controlled by electron beam irradiation. (N.K.)