Effects of Reduced Chemical Vapor Deposition Environment on Growth and Optical Characteristics of TiO₂ Nanobelts

TiO_2−δ nanobelts were self-catalytically grown at 510 °C on bare Si (100) substrates using metallorganic chemical vapor deposition. The nanobelt formation was critically affected by the partial pressure of oxygen. The nanobelts were grown when supplying only Ar or a mixed gas of Ar (90%) and H₂ (10%), while thin films were formed with an O₂ gas flow of more than 50 cm³ min⁻¹. The nanobelts consisted of ∼20–30 nm size rutile-dominant nanocrystallites. A vapor-solid growth mechanism excluding a liquid phase appeared to control the nanobelt formation. The grown TiO_2−δ nanobelts showed a strong photoluminescence (PL) spectra peak at ∼550 nm due to oxygen vacancies. The nanobelt surface possessed significant amount of oxygen vacancies contributing PL and actively reacting with the environment, indicating promise for photocatalytic and gas sensor applications in a visible light regime.