Local heteroepitaxial growth to promote the selective growth orientation, crystallization and interband transition of sputtered NiO thin films

Abstract

The room temperature growth of highly <111> oriented sputtered NiO thin films on glass and silicon substrates previously covered with a <111> oriented Cu₂O film is reported. The results are compared to those obtained from single layer NiO thin films using the same deposition conditions. Electron microdiffraction analyses indicate that NiO columns are heteroepitaxially grown on the columns of a Cu₂O seed layer. The well-matched atomic configurations between the Cu atoms in the {111} planes of Cu₂O and the O atoms in the {111} planes of NiO may provide a strong driving force to promote this local heteroepitaxial growth. Such heteroepitaxial growth behavior in the columns can significantly improve crystallization. Moreover, valence electron energy loss spectroscopy has been employed to investigate the interband transition properties of the NiO films, which shows that the interband transition intensity can be tuned by this local heteroepitaxial growth.