Room-temperature PL spectra of the TiO
films annealed at different temperatures in N
atmosphere. The as-grown TiO2 film is anatase deposited at a substrate temperature of 250°C. The insert is the areal percentages of the red emission band at 615 nm, the green emission band at 510 nm, and the near-infrared peak at 820 nm, which are derived from multiple-peak Gaussian fitting of the PL spectra, respectively.