| AVS 55th International Symposium & Exhibition | |
| Advanced Surface Engineering | Thursday Sessions |
| Session SE-ThP |
| Session: | Advanced Surface Engineering Poster Session |
| Presenter: | H. Ishikawa, Nagoya University, Japan |
| Authors: | H. Ishikawa, Nagoya University, Japan H. Takeuchi, Nagoya University, Japan Y. Inoue, Nagoya University, Japan O. Takai, Nagoya University, Japan |
| Correspondent: | Click to Email |
1. Introduction Electrochromic (EC) materials change their colors reversibly by applying a burst of electrical charge. Indium nitride (InN) thin films also show EC phenomenon by applying electric potential in a solution. The mechanism of the EC phenomenon in InN is quite unique. We have found that the EC of InN is induced by alternation of surface adsorbates, which means that InN is suitable for high-response EC devices. We have improved the EC properties of InN films by introducing a microvillus-like isolated nanocolumnar structure prepared by glancing-angle deposition (GLAD) in order to expand the effective surface area. However, the microvillus-like structure includes so deep gaps that the EC response property is degraded. In this study, we deposit InN films which have large effective surface area with low-height columnar structure, and their EC response property is investigated. 2. Experimental procedure InN films were deposited on ITO-coated glass plates by using a reactive ion plating system. After evacuation of a deposition chamber, pure N2 gas was fed into the chamber at a constant gas flow of 19.0 sccm. The total pressure was controlled from 1.0 to 7.0 Pa. In order to activate N2 plasma, a 13.56 MHz RF power of 150 W was applied to a RF antenna in the chamber. The crucible for In was resistively-heated to evaporate In metal shots (6N) in the N2 plasma. The substrate holder was rotated during deposition at the angle of 0° or 85° with respect to the vapor fluxes. The crystallinity of the deposited films was investigated by using an X-ray diffractometer (XRD). We investigated the EC properties of the films by using both a UV-Vis spectrophotometer and an EC response measuring unit which consist of a laser diode (650 nm) and a Si photodiode. 3. Results From the XRD profiles, we confirmed that any film deposited in this study has a wurtzite crystal structure. The films deposited without GLAD technique at the total pressure of 1.0 Pa (sample A) and 2.0 Pa (sample B) have a vertical columnar structure with the columnar radius and porosity dependent on the pressure. The EC response of the sample B is faster than that of the sample A. The film deposited with GLAD configuration at the substrate angle of 85° (sample C) has much higher porosity than the samples A and B. Therefore the EC amplitude of the sample C is improved, while the EC response of the sample C was almost same as that of the sample A.