Towards the insulator-to-metal transition at the surface of ion-gated nanocrystalline diamond filmsErik Piatti, Francesco Galanti, Giulia Pippione, Alberto Pasquarelli and Renato S. GonnelliEur. Phys. J. Special Topics, 228 3 (2019) 689-696DOI: https://doi.org/10.1140/epjst/e2019-800188-9