The metal-insulator transition in amorphous Si1-cNic: so, was Mott right after all

We study the metal-insulator transition in two sets of amorphous Si1-cNic films, prepared by. different, electron-beam-evaporation-based technologies. Analysing the logarithmic temperature derivative of the conductivity, w = dlns/dlnT, we observe characteristic minima in the insulating region. Both the minimum value of w and the corresponding temperature seem to tend to zero as the transition is approached. This leads to the conclusion that the transition in Si1-cNic is very likely discontinuous at zero temperature in agreement with Mott's original views.