Naturally asymmetrical double-Schottky barrier model: Based on observation of bicrystal

Abstract

ZnO bicrystals with specific coincidence site lattice twist boundaries are manufactured for investigation. Asymmetrical I-V behaviors occur with maximum nonlinear coefficient of forward direction tenfold of reverse one. Energy dispersion spectra measurement reveals the nonuniform distributions of elements such as bismuth and oxygen in the grain boundary region. This reflects a higher Schottky barrier formed at Zn-polar face than that at O-polar face, which is confirmed by capacitance-voltage method. Such natural asymmetry may result from the effect of spontaneous polarization of polar surfaces of ZnO. Finally, simulation results prove the validity of the asymmetrical model proposed. © 2012 American Institute of Physics.