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Structure and photoluminescence of the TiO2 films grown by atomic layer deposition using tetrakis-dimethylamino titanium and ozone.

Jin C, Liu B, Lei Z, Sun J - Nanoscale Res Lett (2015)

Bottom Line: The amorphous TiO2 film crystallizes to anatase TiO2 phase with annealing temperature ranged from 300°C to 1,100°C in N2 atmosphere, while the anatase TiO2 film transforms into rutile phase at a temperature of 1,000°C.Photoluminescence from anatase TiO2 films contains a red band at 600 nm and a green band at around 515 nm.A blue shift of the photoluminescence spectra reveals that the defects of under-coordinated Ti(3+) ions transform to surface oxygen vacancies in the anatase TiO2 film annealing at temperature from 800°C to 900°C in N2 atmosphere.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, School of Physics, Nankai University, Weijin Road 94, Tianjin, 300071 China.

ABSTRACT
TiO2 films were grown on silicon substrates by atomic layer deposition (ALD) using tetrakis-dimethylamino titanium and ozone. Amorphous TiO2 film was deposited at a low substrate temperature of 165°C, and anatase TiO2 film was grown at 250°C. The amorphous TiO2 film crystallizes to anatase TiO2 phase with annealing temperature ranged from 300°C to 1,100°C in N2 atmosphere, while the anatase TiO2 film transforms into rutile phase at a temperature of 1,000°C. Photoluminescence from anatase TiO2 films contains a red band at 600 nm and a green band at around 515 nm. The red band exhibits a strong correlation with defects of the under-coordinated Ti(3+) ions, and the green band shows a close relationship with the oxygen vacancies on (101) oriented anatase crystal surface. A blue shift of the photoluminescence spectra reveals that the defects of under-coordinated Ti(3+) ions transform to surface oxygen vacancies in the anatase TiO2 film annealing at temperature from 800°C to 900°C in N2 atmosphere.

No MeSH data available.


XPS spectra of Ti 2p states from the TiO2films. Samples were annealed at 1,000°C after removing 3-nm surface layer by Ar+ ion sputtering (a); annealed at 1,000°C without Ar+ ion sputtering (b); and annealed at 800°C without Ar+ ion sputtering (c). The dashed curves are multiple-peak Gaussian fitting of the Ti 2p3/2 peak with two components from the valence states of Ti4+ (blue) and Ti3+ (red).
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Fig9: XPS spectra of Ti 2p states from the TiO2films. Samples were annealed at 1,000°C after removing 3-nm surface layer by Ar+ ion sputtering (a); annealed at 1,000°C without Ar+ ion sputtering (b); and annealed at 800°C without Ar+ ion sputtering (c). The dashed curves are multiple-peak Gaussian fitting of the Ti 2p3/2 peak with two components from the valence states of Ti4+ (blue) and Ti3+ (red).

Mentions: XPS spectroscopy was studied after annealing the as-grown amorphous TiO2 films at different temperatures. Figure 9 shows the XPS peaks of Ti 2p3/2 and Ti 2p1/2 from the TiO2 film annealed at 1,000°C after removing 3-nm surface layer by Ar+ ion sputtering (a), the film annealed at 1,000°C without Ar+ ion sputtering (b), and the film annealed at 800°C without Ar+ ion sputtering (c). The binding energies of Ti 2p3/2 and Ti 2p1/2 peaks of Ti4+ ions in the sample annealed at 1,000°C are located at about 458.75 and 464.48 eV, respectively. After the removal of 3-nm surface layer by Ar+ ion sputtering, the Ti 2p3/2 peak shifts to lower energy at 458.54 eV and a shoulder peak at a lower energy of 457.0 eV appears. Multiple-peak Gaussian fitting of the spectrum indicates that the peak at lower energy belongs to the valence state of Ti3+ ions in the TiO2 film, which are formed by Ar+ ion sputtering, as reported in ref. [32,45,46]. The presence of the Ti3+ states in the films causes a small shift of the 2p3/2 peak of Ti4+ ions to lower energy compared to the un-sputtered one in Figure 9b. As a consequence, comparing the 2p3/2 peak of Ti4+ in the sample annealed at 800°C (c) with the one annealed at 1,000°C (b), a slight shift of Ti 2p3/2 peak from 458.75 to lower energy of 458.46 eV was also observed for the sample annealed at 800°C (c). This suggests that a small amount of trivalent Ti3+ ions exist in the sample annealed at 800°C. The relative concentration of the Ti3+ ions with respect to the total Ti atoms in the annealed anatase TiO2 films can be calculated from the integrated intensity of the 2p3/2 peak of Ti3+ ions (red dashed peak), which was derived by multiple-peak Gaussian fitting of the Ti 2p3/2 peak of the XPS, as shown by the dashed curves in Figure 9.Figure 9


Structure and photoluminescence of the TiO2 films grown by atomic layer deposition using tetrakis-dimethylamino titanium and ozone.

Jin C, Liu B, Lei Z, Sun J - Nanoscale Res Lett (2015)

XPS spectra of Ti 2p states from the TiO2films. Samples were annealed at 1,000°C after removing 3-nm surface layer by Ar+ ion sputtering (a); annealed at 1,000°C without Ar+ ion sputtering (b); and annealed at 800°C without Ar+ ion sputtering (c). The dashed curves are multiple-peak Gaussian fitting of the Ti 2p3/2 peak with two components from the valence states of Ti4+ (blue) and Ti3+ (red).
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Related In: Results  -  Collection

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Fig9: XPS spectra of Ti 2p states from the TiO2films. Samples were annealed at 1,000°C after removing 3-nm surface layer by Ar+ ion sputtering (a); annealed at 1,000°C without Ar+ ion sputtering (b); and annealed at 800°C without Ar+ ion sputtering (c). The dashed curves are multiple-peak Gaussian fitting of the Ti 2p3/2 peak with two components from the valence states of Ti4+ (blue) and Ti3+ (red).
Mentions: XPS spectroscopy was studied after annealing the as-grown amorphous TiO2 films at different temperatures. Figure 9 shows the XPS peaks of Ti 2p3/2 and Ti 2p1/2 from the TiO2 film annealed at 1,000°C after removing 3-nm surface layer by Ar+ ion sputtering (a), the film annealed at 1,000°C without Ar+ ion sputtering (b), and the film annealed at 800°C without Ar+ ion sputtering (c). The binding energies of Ti 2p3/2 and Ti 2p1/2 peaks of Ti4+ ions in the sample annealed at 1,000°C are located at about 458.75 and 464.48 eV, respectively. After the removal of 3-nm surface layer by Ar+ ion sputtering, the Ti 2p3/2 peak shifts to lower energy at 458.54 eV and a shoulder peak at a lower energy of 457.0 eV appears. Multiple-peak Gaussian fitting of the spectrum indicates that the peak at lower energy belongs to the valence state of Ti3+ ions in the TiO2 film, which are formed by Ar+ ion sputtering, as reported in ref. [32,45,46]. The presence of the Ti3+ states in the films causes a small shift of the 2p3/2 peak of Ti4+ ions to lower energy compared to the un-sputtered one in Figure 9b. As a consequence, comparing the 2p3/2 peak of Ti4+ in the sample annealed at 800°C (c) with the one annealed at 1,000°C (b), a slight shift of Ti 2p3/2 peak from 458.75 to lower energy of 458.46 eV was also observed for the sample annealed at 800°C (c). This suggests that a small amount of trivalent Ti3+ ions exist in the sample annealed at 800°C. The relative concentration of the Ti3+ ions with respect to the total Ti atoms in the annealed anatase TiO2 films can be calculated from the integrated intensity of the 2p3/2 peak of Ti3+ ions (red dashed peak), which was derived by multiple-peak Gaussian fitting of the Ti 2p3/2 peak of the XPS, as shown by the dashed curves in Figure 9.Figure 9

Bottom Line: The amorphous TiO2 film crystallizes to anatase TiO2 phase with annealing temperature ranged from 300°C to 1,100°C in N2 atmosphere, while the anatase TiO2 film transforms into rutile phase at a temperature of 1,000°C.Photoluminescence from anatase TiO2 films contains a red band at 600 nm and a green band at around 515 nm.A blue shift of the photoluminescence spectra reveals that the defects of under-coordinated Ti(3+) ions transform to surface oxygen vacancies in the anatase TiO2 film annealing at temperature from 800°C to 900°C in N2 atmosphere.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, School of Physics, Nankai University, Weijin Road 94, Tianjin, 300071 China.

ABSTRACT
TiO2 films were grown on silicon substrates by atomic layer deposition (ALD) using tetrakis-dimethylamino titanium and ozone. Amorphous TiO2 film was deposited at a low substrate temperature of 165°C, and anatase TiO2 film was grown at 250°C. The amorphous TiO2 film crystallizes to anatase TiO2 phase with annealing temperature ranged from 300°C to 1,100°C in N2 atmosphere, while the anatase TiO2 film transforms into rutile phase at a temperature of 1,000°C. Photoluminescence from anatase TiO2 films contains a red band at 600 nm and a green band at around 515 nm. The red band exhibits a strong correlation with defects of the under-coordinated Ti(3+) ions, and the green band shows a close relationship with the oxygen vacancies on (101) oriented anatase crystal surface. A blue shift of the photoluminescence spectra reveals that the defects of under-coordinated Ti(3+) ions transform to surface oxygen vacancies in the anatase TiO2 film annealing at temperature from 800°C to 900°C in N2 atmosphere.

No MeSH data available.