Photocatalytic property and deep levels of Nb-doped anatase TiO2 film grown by metalorganic chemical vapor depostion

A Nb-doped anatase TiO2 (Nb: 5 at%) film was grown on a SrTiO3(001) substrate by metalorganic chemical vapor deposition. Deep level transient spectroscopy analysis revealed that this film possessed two kinds of deep levels due to the Nb ions, which were found to exist at 0.32 eV and 0.67 eV below the bottom of the conduction band. The photocatalytic activity of this film was low compared with that of the undoped anatase film, suggesting that the deep levels acted as recombination centers of photoexcited electron-hole pairs.