The growth process of ZrO2 thin films, deposited on Pt substrates by metallorganic chemical vapor deposition using zirconium tetraisopropoxide as a precursor, has been studied using a rotating-polarizer multichannel ellipsometer equipped with a charge-coupled device detector. Spectroscopic ellipsometry (SE) data were collected in a wavelength range of 470-790 nm with a wavelength resolution of ∼1 nm and a repetition period of 1 s. The SE data could be explained by one-layer and two-layer optical models, which presume a nucleation and coalescence mechanism for the deposition of ZrO2 films. In the initial state of growth, ZrO2 clusters are nucleated and grow into islands, which can be simulated by a single nucleating layer. When the cluster islands reach a critical size, they come into contact with one another and a bulk layer grows under a nucleation-generated roughness layer. The growth of the bulk layer starts when the nucleation layer reaches ∼8 nm thickness. The surface roughness layer stays at ∼9 nm thickness during the growth stage of the bulk layer, independent of deposition temperature. The substrate temperature has strong influence on the growth rate and the ZrO2 volume fraction of the bulk layer. The bulk layer formed at 350°C has the highest ZrO2 volume fraction (0.93) and a high growth rate (0.34 nm s 1). The additional evolution of surface roughness, characterized by a sharp increase in the surface layer thickness, occurs when the deposition is carried at substrate temperatures higher than 400°C.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry