Atomic layer deposition of Nb-doped TiO2: Dopant incorporation and effect of annealing

Berghuis, Wilhelmus J. H.; Melskens, Jimmy; Macco, Bart; Basuvalingam, Saravana Balaji; Verheijen, Marcel A.; Kessels, W.M.M.

doi:10.1116/1.5134743

Cited by 17 publications

(5 citation statements)

References 68 publications

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“…In 2005, Furubayashi et al [6] prepared Nb-doped anatase TiO 2 (TNO) films on a SrTiO 3 substrate by pulsed laser deposition (PLD) method, the excellent resistivity (2∼3×10 −4 Ω cm) and visible transmittance (>90%) of the innovated film are comparable to that of typical TCOs. Subsequently, other researchers studied the properties of TNO films created by different preparation methods [7][8][9][10][11][12]. TNO is expected to become the next generation of innovated TCO material.…”

Section: Introductionmentioning

confidence: 99%

Effects of Nb concentration on Nb-doped anatase TiO₂: DFT + U calculations

Xiao¹,

Wang²,

Zhu³

et al. 2022

Phys. Scr.

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The crystal structure, formation energy, electronic structure, electrical properties and optical properties of anatase TiO2 with various Nb concentrations were studied by first-principles calculations based on density functional theory (DFT) and the Hubbard U correction. Firstly, the crystal structures of TiO2 with various Nb concentrations were optimized successfully. The higher concentrations of Nb facilitate the synthesis of Nb-doped TiO2 systems in an O-rich environment. Furthermore, the band structures and density of states prove that the electronic structure of Nb-doped TiO2 is mainly transformed by the hybridization of Ti 3d, Nb 4d and O 2p states. Next, broadening of the valence band and occupied states at the bottom of the conduction band enhance the conductivity of Nb-doped TiO2, and the conductivity reaches the maximum value at the high Nb-doping concentration of 6.25 at.%. Last but not least, the calculated optical properties show that the absorption edge of Nb-doped TiO2 produces an blue shift. TiO2 with Nb-doping concentration below 14.58 at.% exhibits the high transmittance in the visible region.

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Section: Introductionmentioning

confidence: 99%

Effects of Nb concentration on Nb-doped anatase TiO₂: DFT + U calculations

Xiao¹,

Wang²,

Zhu³

et al. 2022

Phys. Scr.

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“…Compared with that of undoped TiO 2 , the Raman characteristic peak position of Ti–Nb–O nanotubes had almost no change, but the intensity was decreased. This could be explained by the decrease of crystallinity caused by Nb doping since entering Nb 5+ into the TiO 2 lattice could decrease the grain size and cause lattice distortion to some extent. − On the other hand, V O /Ti–Nb–O nanotubes showed a further decrease in Raman characteristic peak intensity and an increase in the full width at half maximum. Raman peaks of V O /Ti–Nb–O exhibited a blue shift, a decrease in intensity, and an increase in the half-height width, which was due to the vibration of the crystal structure and the non-metrological effect caused by oxygen vacancies. , …”

Section: Resultsmentioning

confidence: 99%

Reduced Ti–Nb–O Nanotube Photoanode with Bulk-Phase Nb Doping and Surface Oxygen Vacancy Engineering for Enhanced Photoelectrochemical Water Splitting

Dong

Qin

et al. 2022

Energy Fuels

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Improving optical absorption and photogenerated electron−hole separation−transport performances of TiO 2 -based nanostructures are considered as key strategies for realizing high-efficiency photoelectrochemical (PEC) water splitting. In this work, we successfully prepared V O /Ti−Nb−O nanotubes through bulk-phase Nb doping with surface electrochemical reduction-introduced oxygen vacancies for an enhanced PEC performance. Microstructure analysis combined with density functional theory calculation revealed that synergistic Nb doping with oxygen vacancy self-doping could drive the Fermi level shift toward the conduction band and introduce shallow donor energy levels below the conduction band. This could not only improve electrical conductivity of the reduced Ti-based system but also enhance the transport efficiency of photogenerated carriers. Compared with that of pristine TiO 2 (0.38 mA/cm 2 ), the photocurrent density of the V O /Ti−Nb−O increased to 1.72 mA/cm 2 . The solar-tohydrogen efficiency was 0.67%, which was 2.8 times higher than that of intrinsic TiO 2 . This work introduced oxygen vacancies into Ti−Nb−O nanotubes by one-step facile electrochemical reduction, which may provide a potential synergistic strategy for developing new-type and high-efficiency Ti-based nanostructure photoanodes for boosted PEC water splitting.

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“…Comparing n‐ and p‐type TMOs, it appears that extrinsic n‐type doping of TMOs is much more readily available than for p‐type materials, with a wide library of available n‐type dopants such as Al, B, Ga and H for ZnO, Sn, Zn, W, Zr and H for In 2 O 3 and Nb and Ta for TiO 2‐x. 87,92,313–318 Also, as can be clearly seen in Figure 9C) many of the TMO electron contacts such as TiO 2‐x , Nb 2 O 5‐x and ZnO have been found to give good surface passivation to c ‐Si surfaces 81,83,319,320 . This contrasts from most hole‐selective TMOs which often require a dedicated a‐Si:H passivation layer 82,190,321 .…”

Section: Transition Metal Oxidesmentioning

confidence: 98%

Carrier‐selective contacts using metal compounds for crystalline silicon solar cells

Michel

Dréon

Boccard

et al. 2022

Progress in Photovoltaics

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Solar cells rely on the efficient generation of electrons and holes and the subsequent collection of these photoexcited charge carriers at spatially separated electrodes.High wafer quality is now commonplace for crystalline silicon (c-Si) based solar cells, meaning that the cell's efficiency potential is largely dictated by the effectiveness of its carrier-selective contacts. The majority of contacts currently employed in industrial production are based on highly doped-silicon, which can introduce negative side-effects including Auger recombination or parasitic absorption depending on whether the dopants are diffused into the absorber or whether they are incorporated into silicon layers deposited outside the absorber. Given the terawatt scale of deployment of c-Si solar cells, the search for alternative contacting schemes that can offer potential benefits in terms of performance, cost, ease of processing or stability is highly relevant. One such category of contacting schemes, with the potential to avoid the above mentioned issues, is that which employs metal compounds as the 'carrierselective' layer. The last 7 years has seen a surge in interest on this topic and a few promising families of materials have emerged, most prominently the alkali/alkalineearth metal compounds and the transition-metal oxides. The number of successful selective-contact demonstrations of materials within these families is fast increasing with the best solar cell demonstrations now exceeding 23%. However, in addition to improving their efficiency performance, several challenges remain if such contacts are to be considered for industrial adoption. These are mainly associated with poor stability, lack of compatibility with transparent electrodes and inability to be deposited using standard industrial techniques. This review covers the historical developments, current status and future prospects of metal-compound based selective contacts in the context of c-Si photovoltaics.

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Atomic layer deposition of Nb-doped TiO2: Dopant incorporation and effect of annealing

Cited by 17 publications

References 68 publications

Effects of Nb concentration on Nb-doped anatase TiO₂: DFT + U calculations

Effects of Nb concentration on Nb-doped anatase TiO₂: DFT + U calculations

Reduced Ti–Nb–O Nanotube Photoanode with Bulk-Phase Nb Doping and Surface Oxygen Vacancy Engineering for Enhanced Photoelectrochemical Water Splitting

Carrier‐selective contacts using metal compounds for crystalline silicon solar cells

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Atomic layer deposition of Nb-doped TiO2: Dopant incorporation and effect of annealing

Cited by 17 publications

References 68 publications

Effects of Nb concentration on Nb-doped anatase TiO2: DFT + U calculations

Effects of Nb concentration on Nb-doped anatase TiO2: DFT + U calculations

Reduced Ti–Nb–O Nanotube Photoanode with Bulk-Phase Nb Doping and Surface Oxygen Vacancy Engineering for Enhanced Photoelectrochemical Water Splitting

Carrier‐selective contacts using metal compounds for crystalline silicon solar cells

Contact Info

Product

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Effects of Nb concentration on Nb-doped anatase TiO₂: DFT + U calculations

Effects of Nb concentration on Nb-doped anatase TiO₂: DFT + U calculations