High transparency Bi₂Se₃ topological insulator nanoribbon Josephson junctions with low resistive noise properties

Bi₂Se₃ nanoribbons, grown by catalyst-free Physical Vapor Deposition, have been used to fabricate high quality Josephson junctions with Al superconducting electrodes. The conductance spectra (dI/dV) of the junctions show clear dip-peak structures characteristic of multiple Andreev reflections. The temperature dependence of the dip-peak features reveals a highly transparent Al/Bi₂Se₃ topological insulator nanoribbon interface and Josephson junction barrier. This is supported by the high values of the Bi₂Se₃ induced gap and of I_cR_n (where I_c is the critical current and R_n is the normal resistance of the junction) product both of the order of 160 μeV, a value close to the Al gap. The devices present an extremely low relative resistance noise below 1 × 10^-12 μm²/Hz comparable to the best Al tunnel junctions, which indicates a high stability in the transmission coefficients of transport channels. The ideal Al/Bi₂Se₃ interface properties, perfect transparency for Cooper pair transport in conjunction with low resistive noise, make these junctions a suitable platform for further studies of the induced topological superconductivity and Majorana bound states physics.