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.
Applied Physics Letters