Tunneling spectroscopy of superconducting MoN and NbTiN grown by atomic layer deposition

Abstract

A tunneling spectroscopy study is presented of superconducting MoN and Nb${}_{0.8}$Ti${}_{0.2}$N thin films grown by atomic layer deposition (ALD). The films exhibited a superconducting gap of 2meV and 2.4meV respectively with a corresponding critical temperature of 11.5K and 13.4K, among the highest reported $T_c$ values achieved by the ALD technique. Tunnel junctions were obtained using a mechanical contact method with a Au tip. While the native oxides of these films provided poor tunnel barriers, high quality tunnel junctions with low zero bias conductance (below $\sim$10%) were obtained using an artificial tunnel barrier of Al${}_2$O${}_3$ on the film's surface grown $\text{ex situ}$ by ALD. We find a large critical current density on the order of $4\times 10^6$A/cm${}^2$ at $T=0.8T_c$ for a 60nm MoN film and demonstrate conformal coating capabilities of ALD onto high aspect ratio geometries. These results suggest the ALD technique offers significant promise for thin film superconducting device applications.

arXiv comment5 pages, 4 figures

References in corpus (2)

• Improvement and protection of niobium surface superconductivity by Atomic Layer Deposition and heat treatment
• Heteroepitaxy of Group IV-VI Nitrides by Atomic Layer Deposition

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