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

Nickolas Groll; Jeffrey A. Klug; Chaoyue Cao; Serdar Altin; Helmut Claus; Nicholas G. Becker; John F. Zasadzinski; Michael J. Pellin; Thomas Proslier

doi:10.1063/1.4867880

arXiv · 1312.6144

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

Nickolas Groll·Jeffrey A. Klug·Chaoyue Cao·Serdar Altin·Helmut Claus·Nicholas G. Becker·John F. Zasadzinski·Michael J. Pellin·Thomas Proslier

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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 $\textit{ex situ}$ 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.

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Nickolas Groll, Jeffrey A. Klug, Chaoyue Cao, Serdar Altin, Helmut Claus, Nicholas G. Becker, John F. Zasadzinski, Michael J. Pellin, Thomas Proslier. 2013-12-20. Tunneling spectroscopy of superconducting MoN and NbTiN grown by atomic layer deposition. https://doi.org/10.1063/1.4867880

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