Growth and Properties of Co-Evaporated Superconducting YBaCuO Thin Films.

摘要

Growth and properties of high temperature superconductor thin films fabricated with the evaporation method have been investigated. Research efforts have been focused on films in the Y-Ba-Cu-O system. Two processes have been investigated to make YBaCuO films, the post anneal process and the in situ process. With the post anneal process films are crystallized at high temperatures after deposition, whereas with the in situ process films are crystallized at high temperatures during deposition. With both processes YBaCuO thin films have routinely been made, with T(c) above 80 Kelvin. The resulting films are c-axis oriented, and can carry high critical current densities, up to 6,000,000 A/sq cm at 4.2 Kelvin. With the in situ process, films can be made at lower temperatures than with the post anneal process. The lower process temperature reduces the interactions of the film with substrate materials such as sapphire, and one can even make superconducting films on bare silicon. Two deposition systems have been used to make these films, a Balzers deposition system, and a VG deposition system. The VG deposition system was specially designed and built for the fabrication of copper oxide superconductor thin films. The barium fluoride process has been used to make YBaCuO films with the post anneal process.