| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Film Poster Session |
| Presenter: | ChanYang Jeong, Kitami Institute of Technology, Japan |
| Authors: | C.Y. Jeong, Kitami Institute of Technology, Japan Y. Abe, Kitami Institute of Technology, Japan M. Kawamura, Kitami Institute of Technology, Japan K.H. Kim, Kitami Institute of Technology, Japan T. Kiba, Kitami Institute of Technology, Japan |
| Correspondent: | Click to Email |
Platinum group metal oxides, such as iridium (Ir) oxide, ruthenium (Ru) oxide, rhodium (Rh) oxide have been studied for electrochemical applications, because of their high chemical stability and electrical conductivity. However, reports on Rh oxide thin film were very scarce compared to Ir oxide and Ru oxide thin films. In this study, we investigated density, structure and optical properties of Rh oxide thin films and their effects on electrochemical properties.
Rh oxide thin films with a thickness of 100 nm were prepared by sputtering a Rh metal target in O2 or H2O atmosphere on glass, Si, and ITO-coated glass substrates. The substrate temperature was varied from -20 to 130 °C using a Peltier device. The density of the films was measured by X-ray reflectivity (XRR). Crystal structure and chemical bonding state of the films were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. Optical properties were measured by UV-Vis spectroscopy. Electrochemical properties of the Rh oxide thin films were measured in 1M KOH aqueous electrolyte.
From the XRR measurements, the density of the films deposited in H2O atmosphere was found to be lower than that deposited in O2. The density of the films decreased with decreasing substrate temperature and the lowest density of 4.2 g/cm3 was observed for the film deposited at -20 °C in H2O atmosphere. XRD pattern showed that all the films except for the film deposited at 130 °C in O2 atmosphere were amorphous. From the FT-IR spectra, absorption peaks of Rh-O and O-H bonds were observed on all the films. Higher transmittance was obtained for the films deposited in H2O atmosphere compared to that the of films deposited in O2. It was also found that the transmittance of the films increased with decreasing the substrate temperature, which suggests that the films were partially hydrated. As a result of the cyclic voltammetry measurements, the larger transferred charge density (ΔQ) was obtained for the films deposited in the H2O atmosphere compared to that of the films deposited in O2. And the largest ΔQ of 13 mC/cm2 was obtained for the film deposited at -20 °C in H2O atmosphere.
In summary, it was found that the Rh oxide thin film deposited at -20 °C in H2O atmosphere had the lowest density and showed the highest electrochemical activity.