Electrochemical Growth of (0001)-n-ZnO Film on (111)-p-Cu2O Film and the Characterization of the Heterojunction Diode

The (111)-p-Cu2O/(0001)-n-ZnO heterostructure was successfully fabricated using a low-temperature electrodeposition method on an Au(111)/Si(100) substrate. The structural, optical and electrical characterizations were carried out by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, transmission electron microscope-energy dispersive X-ray analysis, optical absorption, photoluminescence, and electrical measurements. Isolated hexagonal columnar ZnO grains deposited at a low cathodic current density and the interface between the ZnO and Cu2O film were clearly observed. The (0002)-oriented continuous ZnO film was deposited on the (111)-Cu2O film at higher cathodic current density, but the metallic Cu layer was formed between the ZnO and Cu2O films by reducing Cu2O to Cu-0 during the ZnO deposition. The Cu2O/isolated-ZnO heterostructure showed an ohmic feature, and the (111)-Cu2O/Cu/(0002)-ZnO heterostructures showed an excellent rectification with the rectification ratio of similar to 10(5). (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3623776] All rights reserved.