Junction Characteristics of an Au/Ba1-xKxBiO3/Niobium-Doped SrTiO3 Structure

Abstract

Au/Ba_1-x K _x BiO₃ and Ba_1-x K _x BiO₃/niobium-doped SrTiO₃, two types of junctions which correspond to the emitter base and base collector in superconducting base transistors, respectively, have been fabricated and studied. The highest T _c end point (T _c0) of 28 K was obtained of thin film Ba_1-x K _x BiO₃ by rf-sputtering method. The Au/Ba_1-x K _x BiO₃ tunnel spectrum showed a clear gap structure and was very close to the ideal Bardeen Cooper Schrieffer theory's (BCS) form with Δ(0)=3.19 meV. The Ba_1-x K _x BiO₃/SrTiO₃(Nb) junction with heavy niobium doping (0.1 wt%) showed tunnellike I-V characteristics. The dI/dV spectrum for a high-T _c superconductor/semiconductor junction displayed the energy gap structure of a superconductor.