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

Bi${}_2$Se${}_3$ nanoribbons, grown by catalyst-free Physical Vapour 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/Bi${}_2$Se${}_3$ topological insulator nanoribbon interface and Josephson junction barrier. This is supported by the high values of the Bi${}_2$Se${}_3$ induced gap and of I${}_c$R${}_n$ (I${}_c$ critical current, R${}_n$ normal resistance of the junction) product both of the order of 160 $\mu$eV, a value close to the Al gap. The devices present an extremely low relative resistance noise below 1$\times$10${}^{-12}$ $\mu$m${}^2$/Hz comparable to the best Al tunnel junctions, which indicates a high stability in the transmission coefficients of transport channels. The ideal Al/Bi${}_2$Se${}_3$ 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.