Ti1-xSnxO2 nanofilms : layer-by-layer deposition with extended Sn solubility and characterization
Tan, Hui Ru
Hui, Hui Kim
Cao, Jian Qing
Leek, Meng Lee
Feng, Yuan Ping
Date of Issue2017
School of Physical and Mathematical Sciences
High quality rutile Ti1-xSnxO2 nanofilms were successfully grown in a layer-by-layer mode at a moderately low temperature of 400 °C using pulsed laser deposition (PLD). High solid solubility of up to x = 0.216 has been achieved in the Ti1-xSnxO2 films despite theoretical prediction by Density functional theory (DFT) of large formation energy (∼5.64 eV) required for the substitutional alloy to exist at such high Sn concentration. The resultant films have smooth interfaces and step-terraced surfaces with well controlled stoichiometry and are optically transparent. Sn L3-edge Extended X-ray absorption fine structure (EXAFS) reveals the substitution of Sn4+ in the Ti4+ lattice sites of TiO2. The lattice spacing along  increases linearly with increment in x due to substitution of Sn4+ ions in the Ti lattice sites of the Ti1-xSnxO2 films. X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering (RBS) show that Sn is uniformly distributed on the surface and in the bulk of the films. These results are crucial when considering Ti1-xSnxO2 with suitable composition for making TiO2 based quantum structures in advanced optoelectronic devices and solar energy materials, where high-quality crystalline thin film-substrates are important.
Applied Surface Science
© 2017 Elsevier B.V. All rights reserved This paper was published in Applied Surface Science and is made available with permission of Elsevier B.V.