Properties of Ti-oxide thin films grown in reactive magnetron sputtering with self-heating target

Abstract

Titanium dioxide thin films have been synthetized by magnetron sputtering in two configurations: using a classical cooled target (cold configuration) or allowing the target temperature to rise under ion bombardment (hot target configuration). In hot configuration, the heated target emits radiations (especially infrared ones) which affect the thin film growth. The target is pure titanium sputtered in presence of argon and dioxygen gases. The crystalline quality, morphology and structure of thin films have been studied on two substrates: thermally grown SiO2 (500 nm)/Si and c-cut sapphire. X-ray diffraction analyses revealed that anatase phase is mainly obtained in both configurations. Texture factors evidenced different main orientations: in cold target the anatase (004) peak tends to be preferred, whereas when a hot target is used, the (112) family plane is furthered. Microscopy analyses showed that the morphology changed depending on the configuration, which could be attributed to an increase of the adatom mobility at the substrate when the target is hot. Optical transmission measurements performed on titanium dioxide thin films deposited onto sapphire substrates showed that optical band gaps may be tuned depending on the configuration used during deposition.