Electrical Conductivity in Polycrystalline Copper Oxide Thin Films

This study presents a preliminary investigation on the electrical properties and the electronic structure of the copper‐oxygen system. Thin films, prepared by high vacuum sputtering on glass and MgO substrates, were oxidised both at constant temperatures and by heating continuously from a low to a high temperature, and the variations in the resistance with oxidation were measured. The final oxide was found to be CuO. The room temperature resistance after oxidation is very much higher than that before oxidation, indicating a transition from metal to insulator. At oxidation temperatures below 600 K, the conductivity decreased gradually; a steeper decrease occurred at higher temperatures when an apparent semiconducting behaviour was observed in some cases. At temperatures above 600 K, the behaviour of the conductivity followed the form σ( T ) = σ(0) + α T β, which suggested weak localization or electron‐electron interaction.