We analyze the influence of the surface passivation produced by oxides on the superconducting properties of γ-Mo2N 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 Mo2N 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 ≈ 45 ps. This value is promising for its applications in single-photon detectors.
@article{arxiv.2106.10781,
title = {Nanocrystalline superconducting $\gamma$-Mo$_2$N ultra-thin films for single-photon detectors},
author = {J. A. Hofer and M. Ginzburg and S. Bengio and N. Haberkorn},
journal= {arXiv preprint arXiv:2106.10781},
year = {2021}
}