Interface physics of TiO₂ anatase and rutile growth on c-cut sapphire substrates using PLD technique

Titanium dioxide (hereafter, titania or TiO₂) is a well-studied material, but despite of its 100 year history we still don't know everything about this material. For the last few decades it used to be thought that only one of tetragonal phases of titania - rutile - can be grown on c-cut sapphire substrates. As a part of this study we grew both anatase and rutile titania on c-cut sapphire by manipulating pulsed laser deposition (PLD) growth parameters, such as substrate temperature, background gas pressure, laser pulse repetition rate and laser pulse energy. All films were analyzed using X-ray diffraction technique. The resulting films show pure anatase and pure rutile structures.
In order to explain the possibility of growing anatase titania on c-cut sapphire despite a large (over 20%), lattice mismatch grazing incidence X-ray diffraction (GID) technique was implemented. GID revealed presence of an intermediate layer between films and the substrate, which provided a lower lattice mismatch between anatase and sapphire. The results will be further analyzed and confirmed using X-ray Photoelectron Spectroscopy and Transmission Electron Microscopy.