Photoluminescence and photoreactivity affected by oxygen defects in crystal-oriented rutile thin film fabricated by molecular precursor method

This article describes the post-annealing treatment of a rutile thin film, which was fabricated on a quartz glass substrate by heat treating a precursor film in air for 15–60 min by using a process involving a Ti complex of EDTA. The transparent, crack-free rutile thin films thus obtained were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy. The photoluminescence emission band of the post-annealed rutile thin films appeared at ca. 800 nm, which is in the extraordinary low-energy region, although no emission band in the region could be observed for the rutile thin film before annealing. It was revealed that the extraordinary emission band of the thin films at 800 nm is strongly related both to the orientation of the constituent crystals along the (110) plane and to the incorporation of O atoms into the O-defect sites that were in the rutile thin film before the post-annealing treatment.