The electrical property dependence of disordered copper oxide on oxygen content

We have deposited disordered copper oxide films on glass substrates, with varying oxygen to copper ratios, by the reactive sputtering method. The variation in the ratio is enough to take the system from having disordered metallic like conduction at low oxygen content to hopping like behaviour at higher oxygen content. The hopping like behaviour is described by an unusual band structure, where Mott-variable range hopping is seen at lower temperatures and electron-electron variable range hopping at higher temperatures in some samples. The metallic region shows the expected effects of quantum corrections to the conductivity, with the often seen influence of spin-orbit scattering in copper. The transition between the hopping and metallic state is of the percolation type, where the conduction path between Cu islands is broken as the oxygen content increases.