Thin films of heavily boron doped plasma-enhanced chemical vapour deposition grown nanocrystalline diamond were investigated experimentally by means of low-temperature transport methods and noise analysis. The influence of grain boundaries upon superconductivity and other related quantum phenomena observed in this system was treated by using a phenomenological model according to which the superconducting diamond grains in the film were interconnected by a single link, or a few weak links, having characteristic dimensions in the nanometre range. Comparing the experimental values of critical current and current-induced Josephson's noise in the superconductivity transition region, with the figures predicted by the present model, its relevance to the description of boron-doped nanocrystalline diamond was proved.

Grain Boundary Effects in Nanocrystalline Diamond. J.J.Mareš, P.Hubík, J.Krištofik, M.Nesládek: Physica Status Solidi A, 2008, 205[9], 2163-8