Electric properties of contacts to HTS thin films at current densities J >J(c)

The role of superconducting film contacts when transporting critical curren t density was investigated using d.c. and electric short pulses. It was fou nd that both d.c. and pulse current exceeding critical current I-c dissipat e at the film contacts, i.e. at the metal/superconductor planar interface c ontaining an intermediate layer of degraded superconductor. Current I > I-c dissipation at the contacts initiates electric-thermal destruction of the superconducting film cathode. The resulting damage to the film is explained in terms of the formation of a (p/i/n) junction at the normal-metal(n)/mix ed-state super conductor(p) interface containing (i) layer of low electric conductivity.