Electronic Band Structure of Transparent Conductor: Nb-Doped Anatase TiO<sub>2</sub>

Hitosugi, Taro; Kamisaka, Hideyuki; Yamashita, Koichi; Nogawa, Hiroyuki; Furubayashi, Yutaka; Nakao, Shin-ichi; Yamada, Naoomi; Chikamatsu, Akira; Kumigashira, Hiroshi; Oshima, Masaharu; Hirose, Yasushi; Shimada, Toshihiro; Hasegawa, Tetsuya

doi:10.1143/apex.1.111203

Cited by 142 publications

(143 citation statements)

References 22 publications

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“…The whole set of data indicate therefore that in our materials, as expected for n-type systems, the Fermi level lies, in an higher position with respect to the undoped material, very close to the conduction band minimum (CBM) as aspected for Nb-doped system 53 ore, in some case, even inside the conduction band in agreement with findings predicting by theoretical approach 54,55 .…”

Section: Xps Characterizationsupporting

confidence: 90%

Fluorine- and Niobium-Doped TiO₂: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

et al. 2014

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Section: Xps Characterizationsupporting

confidence: 90%

Fluorine- and Niobium-Doped TiO₂: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

et al. 2014

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“…The electron effective mass was recently measured via ARPES to be around m * e = 0.7m e (where m e is the bare electron mass) for excess carrier densities n ∼ 10 18 ÷10 19 cm −3 [11], which is larger than the one predicted by band structure calculations (m * e = 0.42m e [57]) due to the polaronic dressing of the electrons. For higher carrier density regimes, m * e is expected to decrease towards the values predicted by band structure calculations due to an effective screening of the electron-phonon interaction [11].…”

Section: S6 Choice Of the Electron Effective Massmentioning

confidence: 89%

“…3). Due to the high carrier densities involved in our experiment, we use the value of the electron effective mass reported by band theory m * e = 0.42m e (see §S5 for the choice of m * e ) [57]. On the other hand, to provide an estimate of m * h from the details of the measured electronic structure, we rely on recent ARPES data for the top of the VB along the Γ-X direction in the case of an excess carrier density n ∼ 10 19 cm −3 [21].…”

mentioning

confidence: 99%

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

et al. 2018

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The recent identification of strongly bound excitons in room temperature anatase TiO 2 single crystals and nanoparticles underscores the importance of bulk many-body effects in samples used for applications. Here, for the first time, we unravel the interplay between many-body interactions and correlations in highly-excited anatase TiO 2 nanoparticles using ultrafast two-dimensional deepultraviolet spectroscopy. With this approach, under non-resonant excitation, we disentangle the optical nonlinearities contributing to the bleach of the lowest direct exciton peak. This allows us to clock the ultrafast timescale of the hot electron thermalization in the conduction band with unprecedented temporal resolution, which we determine to be < 50 fs, due to the strong electronphonon coupling in the material. Our findings call for the design of alternative resonant excitation schemes in photonics and nanotechnology.1 arXiv:1703.07818v2 [cond-mat.mes-hall] 13 Jan 2018In the last decades, anatase TiO 2 has attracted huge interest as one of the most promising materials for a variety of challenging applications, ranging from photocatalysis [1,2] and photovoltaics [3] to sensors [4,5]. Since these technologies involve charge transport, thermalization and localization, they call for studies of the fast electron and hole dynamics, which provide a deep knowledge of the nature of the photogenerated/injected charge carriers and of the energy balance therein. These processes intimately depend on the details of the electronic structure and the presence of many body-effects in the material. Since anatase TiO 2 is a d 0 transition metal oxide, strong electron-electron correlations do not play a substantial role in the electronic structure [6]. Hence, this solid can be classified within the simple band insulator scheme, in which the forbidden energy gap arises as a result of band theory and is not a consequence of the strong on-site Coulomb interaction. However, different to conventional band insulators, anatase TiO 2 represents a peculiar example in which electron-phonon interaction and electron-hole correlation become relatively strong and influence the optical spectra. On the one hand, the presence of a moderately large electron-phonon coupling in anatase TiO 2 has often been invoked to interpret experimental results naturally pointing to the polaronic (self-trapped) picture [7][8][9][10][11][12][13]. Notable examples include the low temperature green photoluminescence (PL) due to self-trapped excitons [14][15][16][17][18][19][20] and the room temperature electron mobilities whose values are limited by strong scattering with phonons [10]. On the other hand, many-body correlations have been thought to be negligible in this material and, as such, they remained widely unexplored. Recently, by employing state-of-the-art experimental [21] and computational techniques [21][22][23][24][25], the substantial role of electron-hole Coulomb correlations was unravelled in the anatase polymorph of TiO 2 . Strongly bound direct excitons were...

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“…[63][64][65] As for the present work, it is crucial to understand how the N and Nb codopants . [63][64][65][66][67][68] The picture becomes quite different when both N and Nb are simultaneously added to the anatase lattice ( Figure 5). As already calculated for N doping 9,69 , valence nitrogen states lie in the proximity of the valence band (VB).…”

Section: Electronic Structurementioning

confidence: 99%

Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO₂ Powders of Nanomaterials

et al. 2014

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Electronic Band Structure of Transparent Conductor: Nb-Doped Anatase TiO₂

Cited by 142 publications

References 22 publications

Fluorine- and Niobium-Doped TiO₂: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

Fluorine- and Niobium-Doped TiO₂: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO₂ Powders of Nanomaterials

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Electronic Band Structure of Transparent Conductor: Nb-Doped Anatase TiO2

Cited by 142 publications

References 22 publications

Fluorine- and Niobium-Doped TiO2: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

Fluorine- and Niobium-Doped TiO2: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Nanoparticles

Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO2 Powders of Nanomaterials

Contact Info

Product

Resources

About

Electronic Band Structure of Transparent Conductor: Nb-Doped Anatase TiO₂

Fluorine- and Niobium-Doped TiO₂: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

Fluorine- and Niobium-Doped TiO₂: Chemical and Spectroscopic Properties of Polycrystalline n-Type-Doped Anatase

Unraveling the Cooperative Mechanism of Visible-Light Absorption in Bulk N,Nb Codoped TiO₂ Powders of Nanomaterials