  We use sub-Kelvin scanning tunneling spectroscopy to investigate the
suppression of superconductivity in homogeneously disordered ultrathin MoC
films. We observe that the superconducting state remains spatially homogeneous
even on the films of 3 nm thickness. The vortex imaging suggests the global
phase coherence in our films. Upon decreasing thickness, when the
superconducting transition drops from 8.5 to 1.2 K, the superconducting energy
gap follows perfectly Tc. All this is pointing to a two-stage fermionic
scenario of the superconductor-insulator transition (SIT) via a metallic state
as an alternative to the direct bosonic SIT scenario with a Cooper-pair
insulating state evidenced by the last decade STM experiments.
