Electrical characterization of Schottky contacts to n-MgZnO films

•Growth of polar and nonpolar MgZnO:N films using remote-plasma-enhanced metalorganic chemical vapor deposition•Selection of materials and orientations on Schottky characteristics•Metal vs polymer electrodes including surface treatment•Dipole effect in Schottky interface

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.