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Optical properties and bandgap evolution of ALD HfSiOx films.

Yang W, Fronk M, Geng Y, Chen L, Sun QQ, Gordan OD, Zhou P, Zahn DR, Zhang DW - Nanoscale Res Lett (2015)

Bottom Line: Hafnium silicate films with pure HfO2 and SiO2 samples as references were fabricated by atomic layer deposition (ALD) in this work.Experimental results show that optical constants and bandgap of the hafnium silicate films can be tuned by the film composition, and a nonlinear change behavior of bandgap with SiO2 fraction was observed.This phenomenon mainly originates from the intermixture of d-state electrons in HfO2 and Si-O antibonding states in SiO2.

View Article: PubMed Central - PubMed

Affiliation: Institute of Advanced Nanodevices, School of Microelectronics, Fudan University, No. 220 Handan Road, Shanghai, 200433 China.

ABSTRACT
Hafnium silicate films with pure HfO2 and SiO2 samples as references were fabricated by atomic layer deposition (ALD) in this work. The optical properties of the films as a function of the film composition were measured by vacuum ultraviolet (VUV) ellipsometer in the energy range of 0.6 to 8.5 eV, and they were investigated systematically based on the Gaussian dispersion model. Experimental results show that optical constants and bandgap of the hafnium silicate films can be tuned by the film composition, and a nonlinear change behavior of bandgap with SiO2 fraction was observed. This phenomenon mainly originates from the intermixture of d-state electrons in HfO2 and Si-O antibonding states in SiO2.

No MeSH data available.


Calculatedn(a) andk(b) of the HfSiOxfilms with different SiO2incorporation content.
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Fig2: Calculatedn(a) andk(b) of the HfSiOxfilms with different SiO2incorporation content.

Mentions: Figure 2a shows the refractive index n as a function of photon energy for all samples as deduced from the analysis of the SE results. The n value for HfO2 measured at 550-nm (2.26 eV) wavelength is 1.84, which is similar with the previous report [20]. In addition, as shown in Figure 2a, the index of refraction decreases with the increase of Si concentration in the films. According to the Lorentz-Lorenz relation [21], the refractive index can be related to the evolution of packing density and polarization. Since Si-O bonds tend to be less polar than the corresponding Hf-O bond [22], the increase of Si concentration in the film would lead to a decrease of the film polarization, then lower polarizability results in the lowering of the refractive index.Figure 2


Optical properties and bandgap evolution of ALD HfSiOx films.

Yang W, Fronk M, Geng Y, Chen L, Sun QQ, Gordan OD, Zhou P, Zahn DR, Zhang DW - Nanoscale Res Lett (2015)

Calculatedn(a) andk(b) of the HfSiOxfilms with different SiO2incorporation content.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385042&req=5

Fig2: Calculatedn(a) andk(b) of the HfSiOxfilms with different SiO2incorporation content.
Mentions: Figure 2a shows the refractive index n as a function of photon energy for all samples as deduced from the analysis of the SE results. The n value for HfO2 measured at 550-nm (2.26 eV) wavelength is 1.84, which is similar with the previous report [20]. In addition, as shown in Figure 2a, the index of refraction decreases with the increase of Si concentration in the films. According to the Lorentz-Lorenz relation [21], the refractive index can be related to the evolution of packing density and polarization. Since Si-O bonds tend to be less polar than the corresponding Hf-O bond [22], the increase of Si concentration in the film would lead to a decrease of the film polarization, then lower polarizability results in the lowering of the refractive index.Figure 2

Bottom Line: Hafnium silicate films with pure HfO2 and SiO2 samples as references were fabricated by atomic layer deposition (ALD) in this work.Experimental results show that optical constants and bandgap of the hafnium silicate films can be tuned by the film composition, and a nonlinear change behavior of bandgap with SiO2 fraction was observed.This phenomenon mainly originates from the intermixture of d-state electrons in HfO2 and Si-O antibonding states in SiO2.

View Article: PubMed Central - PubMed

Affiliation: Institute of Advanced Nanodevices, School of Microelectronics, Fudan University, No. 220 Handan Road, Shanghai, 200433 China.

ABSTRACT
Hafnium silicate films with pure HfO2 and SiO2 samples as references were fabricated by atomic layer deposition (ALD) in this work. The optical properties of the films as a function of the film composition were measured by vacuum ultraviolet (VUV) ellipsometer in the energy range of 0.6 to 8.5 eV, and they were investigated systematically based on the Gaussian dispersion model. Experimental results show that optical constants and bandgap of the hafnium silicate films can be tuned by the film composition, and a nonlinear change behavior of bandgap with SiO2 fraction was observed. This phenomenon mainly originates from the intermixture of d-state electrons in HfO2 and Si-O antibonding states in SiO2.

No MeSH data available.