Characterisation of TiO2 Thin Films and Multilayer Antireflective Coatings - SE07

TiO2 films are extensively studied because of their interesting chemical, electrical and optical properties. TiO2 is a high bandgap semiconductor that is transparent to visible light and has excellent optical transmittance. TiO2 has high refractive index and good insulating properties, and as a result it is widely used as protective layer for very large scale integrated (VLSI) circuits and for manufacture of optical elements. Additionally TiO2 films have potential uses for a number of electronic device applications such as dye-sensitized photovoltaic cells as well as antireflective (AR) coatings, gas sensors, electrochromic displays, and planar waveguides. The high dielectric constant of TiO2 allows its consideration as an alternative to silicon dioxide for ultrathin gate oxide dielectrics used in memory and logic devices. Several methods have been used to prepare titania films, and these include chemical vapour deposition (CVD), pulsed laser deposition, reactive sputtering and sol-gel deposition. The sol-gel technique has emerged as one of the most promising techniques as this method produces samples with good homogeneity at low cost. To achieve optimum performance it is important to characterise the optical constants and thicknesses of thin TiO2 layers accurately. In this note, we show how the Spectroscopic Ellipsometry (SE), non-destructive optical technique is particularly suitable for thin film characterisation.