Preferred Orientation in Ti Films Sputter-Deposited on SiO₂ Glass: The Role of Water Chemisorption on the Substrate

Abstract

Ti thin films have been grown on SiO 2 glass layers at 350°C by ultrahigh vacuum magnetron sputtering with a small amount of H 2 O, H 2 or O 2 gas introduction to investigate the influence of adsorption on the crystallographic orientation of the Ti films. In situ reflection high-energy electron diffraction (RHEED) and ex situ X-ray diffraction (XRD) studies showed that a water vapor introduction at the beginning of sputter deposition promotes a highly preferred (002) orientation, whereas H 2 gas or O 2 gas introduction does not affect the orientation. These results indicate that the increase of water chemisorption on the substrate by H 2 O gas introduction and reduction of the surface free energy enhance the self-assembly of the Ti atoms toward the most stable C-axis orientation.