High quality nitrogen doped ZnO films were fabricated on glass substrates by allowing nitrogen atoms from a pregrown tungsten nitride (WN) to be activated and diffused into a pure ZnO film during an in situ post-thermal annealing process. The N doped ZnO film exhibited reproducible electrical properties including a Hall concentration of 3.69x10(18) cm(-3), a mobility of 1.35 cm(2)/V-s , and a resistivity of 10 Omega cm at room temperature, along with corresponding structural results. Further investigation using ZnO p-n homojunctions, which displayed good I-V characteristics with a turn-on voltage of about 3 V, demonstrated that the p-type ZnO growth process can simply form p-type ZnO:N. (C) 2008 American Vacuum Society.