Contribution of dielectrics to frequency and noise of NbTiN   superconducting resonators
  We study NbTiN resonators by measurements of the temperature dependent resonance frequency and frequency noise. Additionally, resonators are studied covered with SiOx dielectric layers of various thicknesses. The resonance frequency develops a non-monotonic temperature dependence with increasing SiOx layer thickness. The increase in the noise is independent of the SiOx thickness, demonstrating that the noise is not dominantly related to the low temperature resonance frequency deviations. 
R. Barends, H. L. Hortensius, T. Zijlstra, J. J. A. Baselmans, S. J.   C. Yates, J. R. Gao, and T. M. Klapwijk