Activation conduction in metallic island films

The differential conductivity of metallic island films of Ti, Co, W, and FeNi is investigated in the vicinity of liquid nitrogen temperatures. It is found that the temperature dependence of the conductivity of metallic island films in the insulator phase varies in accordance with the activation law sigma proportional to T (n) exp(-E/kT). It is shown that the power of temperature in the preexponential factor varies from n = 2 to 1 upon an increase in the film thickness. In thicker films, in which a transition from the insulator to the metal conductivity phase takes place, the temperature dependence of the conductivity increases in proportion to temperature. The mechanism of conduction in metallic island films is discussed. (C) 2004 MAIK "Nauka / Interperiodica".