Spectroscopic ellipsometry of thin film and bulk anatase (TiO2)

Jellison, G. E.; Boatner, L. A.; Budai, J. D.; Jeong, B.-S.; Norton, D. P.

doi:10.1063/1.1573737

Cited by 248 publications

(174 citation statements)

References 36 publications

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“…The k curves of the 300 C deposited TiO 2 showed two explicit peaks at about 3.96 and 4.56 eV, which were identical to the bulk anatase. 25 On contrary, a much smoother saturated ramp, instead of any clear peaks, could be found for the 120 C deposited amorphous TiO 2 . Therefore, it could be concluded that the shapes and positions of the corresponding refractive index curves differentiated with the crystalline phase.…”

Section: B Deposition Rate and Optical Propertiesmentioning

confidence: 93%

Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

Huang

Pandraud

Sarro

2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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TiO 2 is an interesting and promising material for micro-/nanoelectromechanical systems (MEMS/ NEMS). For high performance and reliable MEMS/NEMS, optimization of the optical characteristics, mechanical stress, and especially surface smoothness of TiO 2 is required. To overcome the roughness issue of the TiO 2 films due to crystallization during deposition at high temperatures (above 250 C), low temperature (80-120 C) atomic layer deposition (ALD) is investigated. By lowering the deposition temperature, the surface roughness significantly decreases from 3.64 nm for the 300 C deposited crystalline (anatase phase) TiO 2 to 0.24 nm for the 120 C amorphous TiO 2 . However, the layers deposited at low temperature present different physical behaviors comparing to the high temperature ones. The refractive index drops from 2.499 to 2.304 (at 633 nm) and the stress sharply decreases from 684 to 133 MPa. Superhydrophilic surface is obtained for the high temperature deposited TiO 2 under ultraviolet illumination, while little changes are found for the low temperature TiO 2 . The authors demonstrate that by suitable postdeposition annealing, all the properties of the low temperature deposited films recover to that of the 300 C deposited TiO 2 , while the smooth surface profile (less than 1 nm roughness) is maintained. Finally, micromachining of the low temperature ALD TiO 2 by dry etching is also studied.

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Section: B Deposition Rate and Optical Propertiesmentioning

confidence: 93%

Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

Huang

Pandraud

Sarro

2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…The extracted indices of the refraction (n) and the extinction coefficient (k) of the upper and lower layers as functions of wavelength are shown in Figure 4. The refractive index of the lower layer closes to the refractive index of the anatase TiO2 [35]. The upper layer shows a lower value of the refractive index and a larger value of the extinction coefficient because of its amorphous phase.…”

Section: Characterization Of Ald Tio 2 Thin Filmsmentioning

confidence: 95%

Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

et al. 2016

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Titanium oxide (TiO 2 ) films and TiO 2 /SiN x stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO 2 film by atomic layer deposition, has a surface recombination velocity as low as 14.93 cm/s at the injection level of 1.0 × 10 15 cm −3 . However, the performance of silicon surface passivation of the deposited TiO 2 film declines as its thickness increases, probably because of the stress effects, phase transformation, atomic hydrogen and thermal stability of amorphous TiO 2 films. For the characterization of 66-nm-thick TiO 2 film, the results of transmission electron microscopy show that the anatase TiO 2 crystallinity forms close to the surface of the Si. Secondary ion mass spectrometry shows the atomic hydrogen at the interface of TiO 2 and Si which serves for chemical passivation. The crystal size of anatase TiO 2 and the homogeneity of TiO 2 film can be deduced by the measurements of Raman spectroscopy and spectroscopic ellipsometry, respectively. For the passivating contacts of solar cells, in addition, a stack composed of 8-nm-thick TiO 2 film and a plasma-enhanced chemical-vapor-deposited 72-nm-thick SiN x layer has been investigated. From the results of the measurement of the reflectivity and effective carrier lifetime, TiO 2 /SiN x stacks on Si wafers perform with low reflectivity and some degree of surface passivation for the Si wafer.

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“…The index of anatase is considerably below that of rutile, and tables are not readily available. The many papers on the subject do not present consistent results [42][43][44][45][46]. For example, Dakka et al [42] show different indices for "new target" (NT) and "used target"…”

Section: E Index Of Titanium Dioxidementioning

confidence: 99%

Quantum efficiency modeling for a thick back-illuminated astronomical CCD

Groom

Haque

Holland

et al. 2017

Journal of Applied Physics

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The quantum efficiency and reflectivity of thick, back-illuminated CCD's being fabricated at LBNL for astronomical applications are modeled and compared with experiment. The treatment differs from standard thin-film optics in that (a) absorption is permitted in any film, (b) the 200-500 µm thick silicon substrate is considered as a thin film in order to observe the fringing behavior at long wavelengths, and (c) by using approximate boundary conditions, absorption in the surface films is separated from absorption in the substrate. For the quantum efficiency measurements the CCD's are normally operated as CCD's, usually at T = −140• C, and at higher temperatures as photodiodes. They are mounted on mechanical substrates. Reflectivity is measured on air-backed wafer samples at room temperature. The agreement between model expectation and quantum efficiency measurement is in general satisfactory. * degroom@lbl.gov 2

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Spectroscopic ellipsometry of thin film and bulk anatase (TiO2)

Cited by 248 publications

References 36 publications

Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

Characterization of low temperature deposited atomic layer deposition TiO2 for MEMS applications

Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

Quantum efficiency modeling for a thick back-illuminated astronomical CCD

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