A method to manage the resistivity of n-type ZnO films is presented. It involves the controlled diffusion of Zn at low temperature in N2 atmosphere into the ZnO/Zn/ZnO structure. The structures were made by DC sputtering technique. The diffusion periods were varied from 5 to 30 min. This process allow us to obtain ZnO films with excess of Zn (ZnO:Zn). The electrical characterization showed that the resistivity of the films can be varied from 0.01 to 100 omega-cm, the electron concentration from 10(19) to 10(17) cm(-3) and the carrier mobility from 10 to 40 cm2N-s. The films are nanocrystalline with preferred (002) orientation and crystal size that varies from 13 to 20 nm depending on the diffusion period. The films have a band gap of 3.18 eV and 70% of transmittance in the visible region, these properties were obtained from the transmittance measurements of low-resistivity films. Films have good structural, optical and electrical properties, and could be used in the manufacture of light emitting diodes.