Structural study of TiO2 thin films by micro-Raman spectroscopy

Abstract

Abstract:The Raman spectroscopy method was used for structural characterization of TiO 2 thin films prepared by atomic layer deposition (ALD) and pulsed laser deposition (PLD) on fused silica and single-crystal silicon and sapphire substrates. Using ALD, anatase thin films were grown on silica and silicon substrates at temperatures 125-425 • C. At higher deposition temperatures, mixed anatase and rutile phases grew on these substrates. Post-growth annealing resulted in anatase-to-rutile phase transitions at 750 • C in the case of pure anatase films. The films that contained chlorine residues and were amorphous in their as-grown stage transformed into anatase phase at 400 • C and retained this phase even after annealing at 900 • C. On single crystal sapphire substrates, phase-pure rutile films were obtained by ALD at 425 • C and higher temperatures without additional annealing. Thin films that predominantly contained brookite phase were grown by PLD on silica substrates using rutile as a starting material.

Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

“…No typical rutile peaks were seen even at this relatively high annealing temperature. Indeed, it is reported that no structural transformation to other crystalline phases of ALD TiO 2 for temperatures up to 700 C in air and a sudden change to rutile happened at 750 C. 18 Considering the small roughness and the similar XRD pattern that the annealed TiO 2 has, smooth and high quality TiO 2 MEMS devices can thus be made by this "low temperature deposit and then anneal" method.…”

Conformity and structure of titanium oxide films grown by atomic layer deposition on silicon substrates

“…Besides, higher amounts of crystalline phases can be obtained in annealed films [35,36]. At annealing temperatures lower than 700°C, the crystallization to anatase and at higher temperatures the anatase-to-rutile transformation may proceed [36,37].…”

“…Besides, higher amounts of crystalline phases can be obtained in annealed films [35,36]. At annealing temperatures lower than 700°C, the crystallization to anatase and at higher temperatures the anatase-to-rutile transformation may proceed [36,37]. The impact of postdeposition annealing may depend in certain extent on the phase composition [36] as well as concentration and type of impurities in as-grown films [37].…”

“…At annealing temperatures lower than 700°C, the crystallization to anatase and at higher temperatures the anatase-to-rutile transformation may proceed [36,37]. The impact of postdeposition annealing may depend in certain extent on the phase composition [36] as well as concentration and type of impurities in as-grown films [37]. Thus, the complex optimization of both deposition and annealing process parameters should be performed to obtain films suitable for desired application.…”

Photocatalytic activity of titania layer prepared by oxidizing titanium compounds on titanium plate surface

“…For the Ti and TiN-a plates, broad peaks were observed at around 200-400 and 600 cm −1 , which can be assigned to the amorphous titania formed on the plate surface [24][25][26]. The rutile peaks clearly appeared in the spectra of these plates after heating and their relative intensity increased with an increase in the temperature.…”