Field electron emission from a high-T_c superconductor Bi ₂Sr₂CaCu₂O₈+δ whisker

In this study, field emission (FE) properties of a high-T_c superconductor Bi₂Sr₂CaCu₂O ₈+δ (Bi-2212) whisker as well as the optimization of the sample preparation methods were explored. Either chemical etching or mechanical cutting was undertaken at first in order to sharpen one end of the whisker. Both of the treatments successfully yielded a sharply pointed tip with its radius less than 500 nm. Subsequent preparation treatments in a UHV chamber provided layered patterns in FIM observation, which were very characteristic of those of other layered superconductors. More importantly, the treatments inside the UHV chamber stabilized FE currents to a significant level. The resulting fluctuation was subtle enough to be analyzed the energy distribution curves of the FE electron beams issuing from the superconducting Bi-2212.