Optical and Structural Properties of Nickel Oxide Films Investugated by Ellipsometry

초록

Nickel oxide film is one of the most intensively studied materials for resistance random access memory. However, its switching mechanism is not well understood. In this work, we employed spectroscopic ellipsometry to study the oxidation effect of nickel oxide films. Nickel film on platinum substrate is thermally oxdized in oxygen ambient at various temperatures. It is found that the interface layer is formed between the nickel oxide film and underlying platinum substrate when the oxidation temperature is low. Also, using the effective medium theory, it is found that the optical properties of nickel oxide show the inclusion of nickel element when the nickel film is not fully oxidized. This result is correlated to the I-V characteristics. We present the optical and structural properties of nickel oxide films at different oxidation stages.