Highly conductive TiO2 thin films prepared by EB-modification

Gofuku, Eishi; Toyoda, Y.; Uehara, Yasuhi; Kohara, M.; Nunoshita, Masahiro

doi:10.1016/0169-4332(91)90355-n

Cited by 15 publications

(8 citation statements)

References 21 publications

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“…The shift in the optical band gap to a lower value after annealing at 500 °C might relate to the change in film density and an increase of grain size as also seen on other reports . The optical band gap of crystalline TiO 2 films in this study is higher than that of reported values from 3.2 to 3.5 eV for TiO 2 films . However, the band gap of amorphous TiO 2 reported in this work is very close to the value of 3.66 eV of amorphous TiO 2 reported by Luca and also agrees with modelling work of 3.71 eV by Landmann .…”

Section: Resultssupporting

confidence: 92%

Electrical and optical properties of TiO₂ thin films prepared by plasma‐enhanced atomic layer deposition

Dang

Parala

Kim

et al. 2013

Physica Status Solidi (a)

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We report on the electrical and optical characterisation of the high‐permittivity (high‐κ) TiO2 thin films grown by plasma enhanced atomic layer deposition on Si (100) and glass substrates, respectively. TiO2 films were incorporated in metal‐oxide semiconductor (MOS) capacitor structures with an Al metal gate electrode. The as‐deposited films were amorphous; however upon annealing in the temperature range 500–900 °C, crystalline TiO2 in the anatase phase was formed. This was further confirmed by performing Raman measurements where the characteristic features corresponding to the anatase phase were observed. Transmittance and absorption spectra of the as‐deposited and annealed films were performed by UV–Vis measurements showing more than 70% of transmittance. The formation of stoichiometric TiO2 was revealed by X‐ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS) analysis performed on annealed samples (500–900 °C). The dielectric constants were calculated from capacitance–voltage (C–V) curves of the MOS structure on the as‐deposited film and annealed films revealing a significant improvement of the dielectric constants from 10 to 75 at AC frequencies of 100 kHz for the 700 °C annealed TiO2 thin films. The increase in the dielectric constant for annealed films could be attributed to the transformation of film structure from amorphous to polycrystalline (anatase). However, the transformation of amorphous to crystalline phase, leads to an increase in the leakage current which was also found best fitted with Schottky emission mechanism at moderated electric fields.

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Section: Resultssupporting

confidence: 92%

Electrical and optical properties of TiO₂ thin films prepared by plasma‐enhanced atomic layer deposition

Dang

Parala

Kim

et al. 2013

Physica Status Solidi (a)

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“…Reported experimental energy gap data on variously prepared a-TiO 2 thin films cover an energy range from 3.2 eV to 3.7 eV. 24,[26][27][28][29][30][31][32][33]35,36,127 All these results were obtained from UV-VIS spectroscopy followed by direct or indirect Tauc analysis/plots [128][129][130] to extract the optical gap. This means (αE) 1/2 or (αE) 2 , with α being the absorption coefficient, is plotted versus the photon energy and the linear part of the curves is extrapolated towards the energy scale to define the optical gap.…”

Section: B Electronic Properties Of Amorphous Tiomentioning

confidence: 99%

“…a-TiO 2 is a general starting material (precursor) for the synthesis of various single-crystalline phases by hydrothermal treatment. 16,[21][22][23] In practice a-TiO 2 is commonly produced in the form of thin films prepared by various experimental strategies as direct current (magnetron) sputtering, [24][25][26][27][28] electron-beam evaporation, 29,30 cathodic vacuum arc deposition, 31,32 sol-gel deposition, 33,34 reactive sputtering, and arc ion plating. 35,36 Also dense or porous disordered films of nanocrystallites are commonly produced and referred to as amorphous films.…”

Section: Introductionmentioning

confidence: 99%

“…16 In contrast, predominantly phase transitions upon heating from a-TiO 2 films to anatase and partially to rutile are reported. 27,29,31,[34][35][36] The difference in crystallization behavior of a-TiO 2 has been attributed to a strong dependence on the sample history as precursor chemistry, preparation method, and heat treatment. 16,77 Theoretically, the ratio of edge to vertex linked TiO 6 octahedral building blocks 15,76 has been found to play a major role in the crystallization behavior of a-TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

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Fingerprints of order and disorder in the electronic and optical properties of crystalline and amorphous TiO2

et al. 2012

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We have investigated the structural and electronic properties as well as the linear optical response of amorphous TiO 2 within density functional theory and a numerically efficient density functional based tight-binding approach as well as many-body perturbation theory. The disordered TiO 2 phase is modeled by molecular dynamics. The equivalence to experimentally characterized amorphous phases is demonstrated by atomic structure factors and radial pair-distribution functions. By density functional theory calculations, using both the semilocal Perdew-Burke-Ernzerhof functional and the nonlocal Heyd-Scuseria-Ernzerhof screened hybrid functional, the electronic energy gap is found to be larger than in the crystalline TiO 2 phases rutile and brookite but close to the anatase band gap. The quasiparticle energy gap of amorphous TiO 2 is determined to be 3.7 eV, while the optical gap is estimated to 3.5 eV. The disorder-induced formation of localized electronic states has been analyzed by the information entropy of the charge density distributions. The frequency-dependent optical constants, calculated from the complex dielectric function, have been determined in independent particle approximation. Besides similar absorption characteristics between the most common crystalline phases and amorphous TiO 2 , we find distinct differences in the optical spectra in the energy region between 5 eV and 8 eV. These differences can be assigned to the loss of symmetry in the local atomic structure of the disordered material. While the composition of the crystalline phases rutile, anatase, and brookite is well described by periodic arrangements of distorted TiO 6 octahedra building blocks, the amorphous phase is characterized by partial loss of this octahedral coordination and the disorder-induced formation of under-and over-coordinated Ti ions. This leads to the absence of the characteristic crystal-field splitting of unoccupied Ti 3d states into e g and t 2g like subbands. The optical characteristics of the amorphous phase are interpreted as a superposition of optical transitions that reflect the various local symmetries of the manifold of synthesizable crystalline TiO 2 phases. The linear optical properties, calculated within the independent-particle approximation, are found to be in good agreement with the available experimental data.

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“…But, the rutile phase of TiO 2 is a desirable oxide phase for optical properties. Vacuumdeposited TiO 2 thin films with both anatase and rutile structure have been reported in the literature [5][6][7].…”

Section: Introductionmentioning

confidence: 98%

Cu/TiO2 thin films prepared by reactive RF magnetron sputtering

et al. 2015

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Cu/TiO 2 thin films were deposited on glass substrates by reactive RF magnetron sputtering technique. Crystalline structure, surface morphology and electronic structure were studied using X-ray diffraction (XRD), field emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy (XPS). Transmittance and absorptance of these films were characterized by UV-Vis spectroscopy. XRD patterns demonstrate that TiO 2 films deposited on glass substrate at 300°C are observed to be in pure anatase phase, whereas Cu/TiO 2 films are amorphous in nature at 300°C substrate temperature. The crystallinity of Cu/TiO 2 thin films decreases with increasing the dopant concentrations of Cu in TiO 2 films. XPS studies show that Cu is in ?2 oxidation state in all films. The optical band gap of Cu/TiO 2 films decreases from *3.3 to *2.0 eV with the increase in the copper concentration. Further, antimicrobial studies of Cu/TiO 2 films with *3.9 at.% Cu exhibit high transmittance and best antimicrobial activity against E. coli and S. aureus compared to other doped films.

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Highly conductive TiO2 thin films prepared by EB-modification

Cited by 15 publications

References 21 publications

Electrical and optical properties of TiO₂ thin films prepared by plasma‐enhanced atomic layer deposition

Electrical and optical properties of TiO₂ thin films prepared by plasma‐enhanced atomic layer deposition

Fingerprints of order and disorder in the electronic and optical properties of crystalline and amorphous TiO2

Cu/TiO2 thin films prepared by reactive RF magnetron sputtering

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Highly conductive TiO2 thin films prepared by EB-modification

Cited by 15 publications

References 21 publications

Electrical and optical properties of TiO2 thin films prepared by plasma‐enhanced atomic layer deposition

Electrical and optical properties of TiO2 thin films prepared by plasma‐enhanced atomic layer deposition

Fingerprints of order and disorder in the electronic and optical properties of crystalline and amorphous TiO2

Cu/TiO2 thin films prepared by reactive RF magnetron sputtering

Contact Info

Product

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Electrical and optical properties of TiO₂ thin films prepared by plasma‐enhanced atomic layer deposition

Electrical and optical properties of TiO₂ thin films prepared by plasma‐enhanced atomic layer deposition