Limits...
Effects of doping and annealing on properties of ZnO films grown by atomic layer deposition.

Wang A, Chen T, Lu S, Wu Z, Li Y, Chen H, Wang Y - Nanoscale Res Lett (2015)

Bottom Line: Annealing introduces O vacancies, decreases Zn interstitials, and results in weakening and blue-shifting of the UV emission which is sensitive to annealing atmosphere.It also introduces non-radiative centers and weakens the UV emission.Annealing has little effect on photoluminescence of the doped films, but it degrades undoped and doped ZnO film conductivity dramatically; and the degradation depends on the annealing ambient.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Beijing Normal University, Beijing, 100875 China.

ABSTRACT
Undoped and Al-doped ZnO films were synthesized by atomic layer deposition at 150°C and then annealed at 350°C in different atmospheres. Effects of doping and annealing on the film growth mode and properties were investigated. The undoped film has strong UV emission and weak Zn interstitial emission. Annealing introduces O vacancies, decreases Zn interstitials, and results in weakening and blue-shifting of the UV emission which is sensitive to annealing atmosphere. Al doping induces the film growing with its c-axis parallel to the substrate surface. It also introduces non-radiative centers and weakens the UV emission. Al doping widens the film bandgap, which has a quadratic dependence on Al content. Al doping decreases the film resistivity to 5.3 × 10(-3) Ω · cm. Annealing has little effect on photoluminescence of the doped films, but it degrades undoped and doped ZnO film conductivity dramatically; and the degradation depends on the annealing ambient.

No MeSH data available.


Related in: MedlinePlus

Absorption spectra and optical bandgap of as-grown films. (a) Absorption spectra of as-grown undoped and Al-doped ZnO films; (b) the variation of ZnO optical bandgap with doped Al concentrations derived by Tauc’s relationship, calculated by Vagard’s law, and fitted by polynomial function.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4385034&req=5

Fig5: Absorption spectra and optical bandgap of as-grown films. (a) Absorption spectra of as-grown undoped and Al-doped ZnO films; (b) the variation of ZnO optical bandgap with doped Al concentrations derived by Tauc’s relationship, calculated by Vagard’s law, and fitted by polynomial function.

Mentions: The absorption spectra of the as-grown undoped and Al-doped films are shown in Figure 5a. Both undoped and Al-doped films have strong absorption in the UV region and good transmittance (>90%) in the visible region. The absorption intensity of the undoped ZnO film increases quickly at the absorption edge, and the absorption peak is obvious; while absorption intensity of Al-doped films increases slowly at the absorption edge, and the absorption peaks become unobvious. This indicates that Al doping degrades the film crystal quality. Otherwise, Al doping leads to a blue shift of the film absorption edge and the shift increases monotonically with an increase in Al concentration. This is similar to that reported in [9-12,20]. Al3+ radius is smaller than that of Zn2+ [24]. Substitution of lattice Zn2+ by Al3+ would widen the ZnO bandgap. The blue shift of the absorption edge of the doped films indicates that the doped Al3+ ions are located in lattice sites and form Zn1 −xAlxO alloys. For a direct type of a semiconductor, the optical bandgap Eg could be estimated from the optical absorption spectra using Tauc’s relationship [5]:Figure 5


Effects of doping and annealing on properties of ZnO films grown by atomic layer deposition.

Wang A, Chen T, Lu S, Wu Z, Li Y, Chen H, Wang Y - Nanoscale Res Lett (2015)

Absorption spectra and optical bandgap of as-grown films. (a) Absorption spectra of as-grown undoped and Al-doped ZnO films; (b) the variation of ZnO optical bandgap with doped Al concentrations derived by Tauc’s relationship, calculated by Vagard’s law, and fitted by polynomial function.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385034&req=5

Fig5: Absorption spectra and optical bandgap of as-grown films. (a) Absorption spectra of as-grown undoped and Al-doped ZnO films; (b) the variation of ZnO optical bandgap with doped Al concentrations derived by Tauc’s relationship, calculated by Vagard’s law, and fitted by polynomial function.
Mentions: The absorption spectra of the as-grown undoped and Al-doped films are shown in Figure 5a. Both undoped and Al-doped films have strong absorption in the UV region and good transmittance (>90%) in the visible region. The absorption intensity of the undoped ZnO film increases quickly at the absorption edge, and the absorption peak is obvious; while absorption intensity of Al-doped films increases slowly at the absorption edge, and the absorption peaks become unobvious. This indicates that Al doping degrades the film crystal quality. Otherwise, Al doping leads to a blue shift of the film absorption edge and the shift increases monotonically with an increase in Al concentration. This is similar to that reported in [9-12,20]. Al3+ radius is smaller than that of Zn2+ [24]. Substitution of lattice Zn2+ by Al3+ would widen the ZnO bandgap. The blue shift of the absorption edge of the doped films indicates that the doped Al3+ ions are located in lattice sites and form Zn1 −xAlxO alloys. For a direct type of a semiconductor, the optical bandgap Eg could be estimated from the optical absorption spectra using Tauc’s relationship [5]:Figure 5

Bottom Line: Annealing introduces O vacancies, decreases Zn interstitials, and results in weakening and blue-shifting of the UV emission which is sensitive to annealing atmosphere.It also introduces non-radiative centers and weakens the UV emission.Annealing has little effect on photoluminescence of the doped films, but it degrades undoped and doped ZnO film conductivity dramatically; and the degradation depends on the annealing ambient.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Beijing Normal University, Beijing, 100875 China.

ABSTRACT
Undoped and Al-doped ZnO films were synthesized by atomic layer deposition at 150°C and then annealed at 350°C in different atmospheres. Effects of doping and annealing on the film growth mode and properties were investigated. The undoped film has strong UV emission and weak Zn interstitial emission. Annealing introduces O vacancies, decreases Zn interstitials, and results in weakening and blue-shifting of the UV emission which is sensitive to annealing atmosphere. Al doping induces the film growing with its c-axis parallel to the substrate surface. It also introduces non-radiative centers and weakens the UV emission. Al doping widens the film bandgap, which has a quadratic dependence on Al content. Al doping decreases the film resistivity to 5.3 × 10(-3) Ω · cm. Annealing has little effect on photoluminescence of the doped films, but it degrades undoped and doped ZnO film conductivity dramatically; and the degradation depends on the annealing ambient.

No MeSH data available.


Related in: MedlinePlus