ZnO films were deposited onto Bi2O3/(102)Al2O3 substrates by CVD. Epitaxial relationship was observed between ZnO and Al2O3. This film was made up of 100nm width columnar grains grown normal to the surface of the substrate. The diffusion of Bi to the top surface of the film was ascertained by XPS analysis. A non-linear current-voltage characteristic was observed for this film and was considered to be generated by the diffusion of Bi in the film. This result revealed the possibility of the generation of the non-linear property originated in the same mechanism as that of the sintered body.

Diffusion of Bi into ZnO Film Prepared by CVD and its I-V Characteristics. Funakubo, H., Yonetsu, M., Shinozaki, K., Mizutani, N., Ishikawa, M., Sakai, N., Yokokawa, H.: Key Engineering Materials, 1999, 157-158, 175-80