Josephson junctions and superconducting field effect transistors based on epitaxial Bi2Sr2Can-1CunO2(n+2) thin films

Josephson junctions based on thin films of the Bi₂Sr₂Ca₂Cu₃O_10+δ compound show I_cR_n products compatible with YBa₂Cu₃O_7−δ samples. Using quasiparticle tunneling experiments we found evidence for a superconductor–insulator–superconductor tunneling process via localized states in the barrier. The Bi₂Sr₂CaCu₂O_8+δ compound is investigated regarding possible applications in superconducting field effect devices. We present thin films of four unit cells thickness that are superconducting at 58 K. An inverted metal–insulator–superconductor structure was prepared. From the modulation of the normal state resistance we estimate a carrier density of 7×10¹⁹ cm⁻³ for a superconducting sample. The shift of the transition temperature was 1 K/V. The modulation of the I–V characteristics was demonstrated.