Nanocrystalline superconducting $\gamma$-Mo${}_2$N ultra-thin films for single-photon detectors

Abstract

We analyze the influence of the surface passivation produced by oxides on the superconducting properties of $\gamma$-Mo${}_2$N ultra-thin films. The superconducting critical temperature of thin films grown directly on Si (100) with those using a buffer and a capping layer of AlN are compared. The results show that the cover layer avoids the presence of surface oxides, maximizing the superconducting critical temperature for films with thicknesses of a few nanometers. We characterize the flux-flow instability measuring current-voltage curves in a 6.4 nm thick Mo${}_2$N film with a superconducting critical temperature of 6.4 K. The data is analyzed using the Larkin and Ovchinnikov model. Considering self-heating effects due to finite heat removal from the substrate, we determine a fast quasiparticle relaxation time $\approx$ 45 ps. This value is promising for its applications in single-photon detectors.

arXiv comment14 pages, 6 figures

References in corpus (9)

• Superconducting Nanowire Single-Photon Detectors for Quantum Information
• Strong Pinning in High Temperature Superconductors
• Ultra-fast vortex motion in dirty Nb-C superconductor with a close-to-perfect edge barrier
• High-efficiency superconducting nanowire single-photon detectors fabricated from MoSi thin-films
• Large-area microwire MoSi single-photon detectors at 1550 nm wavelength
• Characterization of thin-film NbN superconductor for single-photon detection by transport measurements
• Local flux-flow instability in superconducting films near Tc
• Effect of the nitrogen-argon gas mixtures on the superconductivity properties of reactively sputtered molybdenum nitride thin films
• Electrical conductivity in extremely disordered molybdenum oxynitrides thin films