Optical and structural investigations on titanium oxynitride films for visible-UV photocatalytic applications

Abstract

We report on the epitaxial growth of titanium oxynitride (TiOxNy) films on α-Al2O3 (0001) substrates by using a pulsed-laser deposition technique and their optical properties. Using TiN as a solid source, N content (y) in the films was tuned by changing the partial pressure of O2 gas. The crystalline phase was found to evolve up to y ≈ 0.4 either from rock-salt type or from rutile-type structures. The optical absorption spectra of the films had two distinct components in regions of 0.44–2.4 eV and 2.4–6 eV, which arise from d–d and charge-transfer transitions, respectively. The former transition decreased with decreasing y and vanished at y ≈ 0.26, where a fundamental absorption edge due to the latter transition was found to be 2.4 eV. The results demonstrate a range of anion compositions in the TiOxNy being suitable for visible-light harvesting applications.

Plasmonic titanium nitride nanomaterials prepared by physical vapor deposition methods

“…The superior optical absorption described so far was the result of a combination of intraband and interband transitions involving O/N 2p and Ti 3d. W doping produced additional intraband excitation pathways from W 5d states to the Ti/W d states, increasing the Titanium oxynitrides prepared by PLD have been recently studied for photocatalytic applications [127,128]. For example, in the work of Roy et al [127], surface oxidation from TiN to TiO x N y could be regulated by tuning the number of laser pulses (150-5000 shots, i.e.…”