The dependence on the temperature of the electrical conductivity during the heat treatment is studied. After this treatment consisting of several successive heating/cooling cycles, the structure of the ZnO films becomes stable and the dependence of the electrical conductivity on the temperature becomes reversible. Two series of ZnO films obtained in similar technological conditions are submitted to thermal treatment in vacuum and air respectively the nature of the electrical conductivity variation during the heating and cooling of the film (when the thermal treatment takes place in air) is discussed.
