L. Miao

Preparation and characterization of polycrystalline anatase and rutile TiO2 thin films by rf magnetron sputtering

Titanium dioxide films with the anatase and rutile single phase were formed on Si substrates by rf sputtering through a precise control of critical parameters. The structure of the films was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the optical properties were evaluated with spectroscopic ellipsometry (SE). Lattice distortion was found in both anatase and rutile films from TEM observation. The obtained refractive indices n exhibit higher values than those reported for thin films due presumably to the density structure of the sputtered films. Optical band gaps were calculated by Tauc plot using the obtained extinction coefficient separately for anatase and rutile, with values larger than those reported for bulk materials. The reasons for the larger band gap might be due to the strain from lattice distortion.

Formation and characterization of TiO2 thin films with application to a multifunctional heat mirror

Thin films of titanium dioxide (TiO 2 ) with desired crystal phase of anatase or rutile were formed by rf sputtering of a TiO 2 target under precisely controlled process parameters. The application of TiO 2 as the antireflection layers of a TiN-based heat mirror was testified. Optical calculation was done for the heat mirror, and an optimized structure with TiO 2 (30 nm)/TiN (30 nm)/TiO 2 (30 nm) was deposited on SiO 2 glass by sequential sputtering. Optical evaluation of the heat mirror was performed by measuring the transmittance/reflectance with a spectrophotometer in wavelengths 250-2500 nm and with a FT-IR system in wavelengths 1-25 μm, respectively. Furthermore, it is suggested that a better and a multifunctional performance can mostly be expected through precise control of the crystal structure of the TiO 2 top layer which acts as a photocatalyst.

Synthesis, microstructure and photoluminescence of well-aligned ZnO nanorods on Si substrate

Abstract Well-aligned zinc oxide (ZnO) nanorods were densely grown on Si substrate using ZnO thin-film seed layer without any catalysts and/ or additives by a simple solid–vapour phase thermal sublimation technique. The growth mechanism can be interpreted as self-catalyst of zinc particles based on vapour–solid (VS) mechanism. High-resolution transmission electron microscopy (HRTEM) image and selected area electron diffraction (SAED) pattern confirmed that the single-crystalline growth of the nanorods were preferentially along c-axis of hexagonal crystal system. High-crystal quality ZnO nanorods with strong near band edge emission centred at 380 nm can be achieved on Si substrate by the introduction of sufficient oxygen during the nanorod growth processing.