We report the characterization of ZnO homojunction fabricated with undoped (n-ZnO) and AlN codoped ZnO (p-ZnO) films by RF magnetron sputtering. We directly doped (codoped) AlN into ZnO to obtain p-ZnO instead of conventional codoping method. The Current-Voltage characteristics of the fabricated p-n junction show a typical rectification behavior. The junction parameters such as ideality factor (11.85), barrier height (0.782 eV) and series resistance (33 k Omega) have been determined using Cheung's method. The barrier height (0.805 eV) determined by Norde's method is also in good agreement with Cheung's method. (c) 2010 Elsevier B.V. All rights reserved.