We report the selection of materials and orientations on characteristics of MgZnO:N based Schottky junctions. The Schottky contacts were fabricated to both polar and nonpolar films with Pt and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) electrodes including surface treatments such as isopropyl alcohol (IPA), hydrochloric acid (HCl), hydrogen peroxide (H2O2), and 3-aminopropyltriethoxysilane (APS). The IPA and HCl treated Pt/MgZnO:N junctions showed Ohmic behavior. The H2O2 treated Pt/MgZnO:N diode showed Schottky behavior for both polar and nonpolar films. The PEDOT:PSS/MgZnO:N diodes showed rectifying characteristics for all surface treatment conditions. The PEDOT:PSS/MgZnO:N Schottky showed minimum current at negative (-Ve) voltage in current density-voltage (J-V) curves with a highest shift of -0.4 V for HCl treated polar film and a low shift of -0.05 V for APS treated nonpolar film. The J-V characteristics of PEDOT:PSS/polar ZnO single crystal with Zn- and O-faces demonstrated that the-Ve voltage shift of minimum current was due to the dipole formation at the interface. The time-lapse J-V curves in dark situation showed enhance-Ve voltage shift for polar c-MgZnO:N, and the dipole effect is weak for nonpolar a-MgZnO:N. The dipole effect in the PEDOT:PSS/polar MgZnO:N Schottky diode was further discussed with energy band diagram. (C) 2013 Elsevier B. V. All rights reserved.