Structural and electrochromic properties of InN thin films

Electrochromic (EC) properties of indium nitride (InN) thin films prepared by r.f. ion plating were correlated with their microstructures. In this study, the deposition rate was varied in order to change the microstructures of the InN films. As for the microstructure, bright field TEM images revealed that the InN films consisted of columnar grains with voids at grain boundaries and the diameter of the columnar grain became small in the film prepared at high deposition rate. On the other hand, the packing factor of the InN films decreased with increase in the deposition rate, simultaneously, the EC reaction was enhanced. In addition, ions in the electrolyte were not intercalated into the columnar grains because XRD profiles of the InN films were not changed by the EC coloration. From these results, it was concluded that the EC reaction of InN films occurred at the interfaces between the voids at grain boundaries and the columnar grains. (C) 1998 Elsevier Science S.A. All rights reserved.